Latin 2 Quiz: Declining 3rd Declension Nouns
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Declining 3rd Declension NounsQuestion 1 of 10

A Latin student is translating the sentence: Rex militem fortem laudavit. She correctly identifies militem as the direct object and wants to rewrite the sentence so that the soldier is now the subject performing the action.

If the student rewrites the sentence so that miles (soldier, 3rd declension, masculine) becomes the subject in the nominative singular, which form of the noun must she use, and what ending distinguishes it from the accusative singular form militem?

The nominative singular is miles, which ends in -s attached directly to the consonant stem milit-, unlike the accusative militem, which adds -em to the same stem.
The nominative singular is militis, which uses the genitive ending -is added to the stem milit-, unlike the accusative militem, which uses the ending -em added to the stem milit-.
The nominative singular is milite, which drops the -m from the accusative militem and simply retains the bare stem with a final -e, following the standard i-stem pattern for masculine nouns.
The nominative singular is militi, which uses the dative singular ending -i added to the stem milit-, and it doubles as the nominative form in 3rd-declension masculine nouns of this type.
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Latin 2 Quiz

Latin 2 Quiz: Declining 3rd Declension Nouns

Practice Declining 3rd Declension Nouns in Latin 2 with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Declining 3rd Declension Nouns, giving you a quick way to practice the rules, question types, and explanations that matter most for Latin 2.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A Latin student is translating the sentence: Rex militem fortem laudavit. She correctly identifies militem as the direct object and wants to rewrite the sentence so that the soldier is now the subject performing the action.

If the student rewrites the sentence so that miles (soldier, 3rd declension, masculine) becomes the subject in the nominative singular, which form of the noun must she use, and what ending distinguishes it from the accusative singular form militem?

  1. The nominative singular is miles, which ends in -s attached directly to the consonant stem milit-, unlike the accusative militem, which adds -em to the same stem. (correct answer)
  2. The nominative singular is militis, which uses the genitive ending -is added to the stem milit-, unlike the accusative militem, which uses the ending -em added to the stem milit-.
  3. The nominative singular is milite, which drops the -m from the accusative militem and simply retains the bare stem with a final -e, following the standard i-stem pattern for masculine nouns.
  4. The nominative singular is militi, which uses the dative singular ending -i added to the stem milit-, and it doubles as the nominative form in 3rd-declension masculine nouns of this type.
Explanation: When working with 3rd-declension nouns in Latin, your first task is to identify the stem — which you find by dropping the -is from the genitive singular. For miles, the genitive is militis, giving you the stem milit-. From there, you build all other forms by adding the appropriate endings to that stem. For the nominative singular of most 3rd-declension masculine and feminine nouns, Latin simply attaches -s directly to the consonant stem. With milit-, that produces miles (the -ts combination naturally contracts to -s). The accusative singular, by contrast, adds -em to the same stem, giving you militem. So when the student rewrites the sentence with the soldier as subject, she needs miles — and that's exactly what answer A describes, making it correct. Answer B confuses the nominative with the genitive. Militis is the genitive singular ("of the soldier"), not the nominative — a classic mix-up when students are still memorizing the full declension chart. Answer C describes milite, which is actually the ablative singular form, used after prepositions like cum or to express means and manner — not the subject form. Answer D offers militi, the dative singular ("to/for the soldier"), and falsely claims it doubles as a nominative, which has no basis in 3rd-declension grammar. A reliable study habit: always learn noun forms in pairs — nominative and genitive together (miles, militis). The genitive reveals the stem and declension class, and everything else builds from there. Mixing up cases is one of the most common errors on Latin exams, so drilling full declension charts pays off quickly.

Question 2

A student needs to fill in the blank: Voces   (rex, king) magnae erant. The sentence means 'The voices of the kings were great.' Which form of rex (3rd declension, masculine, stem reg-) correctly completes the sentence?

  1. regum — the genitive plural, formed by adding -um to the stem reg-, indicating possession by multiple kings and agreeing with the plural context of the sentence. (correct answer)
  2. regis — the genitive singular, formed by adding -is to the stem reg-, indicating that the voices belong to one king rather than to multiple kings as the plural context requires.
  3. reges — the nominative or accusative plural, formed by adding -es to the stem reg-, which would make reges a second subject rather than a possessive modifier of voces.
  4. regibus — the dative or ablative plural, formed by adding -ibus to the stem reg-, which would indicate the kings as recipients or an ablative of means rather than expressing possession.
Explanation: When you see a Latin sentence asking you to express possession — "the voices of the kings" — your first instinct should be to reach for the genitive case, which signals ownership or belonging. The next question is number: does the sentence mean one king or multiple kings? Here, "kings" is plural, so you need the genitive plural. For 3rd declension nouns like rex (stem reg-), the genitive plural is formed by adding -um to the stem: reg- + -um = regum. This gives you "of the kings," perfectly completing Voces regum magnae erant — "The voices of the kings were great." That makes A the correct answer. Now let's examine the distractors. B, regis, is the genitive singular (reg- + -is), meaning "of the king" (just one). It correctly uses the genitive case but fails the number requirement — the sentence demands a plural possessor. C, reges, is nominative or accusative plural, built with -es. This form doesn't express possession at all; it would awkwardly insert a second subject or a stray accusative into the sentence rather than modifying voces. D, regibus, uses the -ibus ending shared by the dative and ablative plural. Neither of those cases expresses possession — they indicate recipients, instruments, or circumstances, none of which fits "of the kings." A helpful study tip: whenever you translate a phrase with "of" in English, default to the genitive in Latin, then immediately check singular vs. plural to choose the right ending.

Question 3

The noun nox, noctis (f., night, 3rd declension, stem noct-) is a consonant-stem noun. A student must write 'by night' using the ablative singular. She also recalls that ignis, ignis (m., fire, 3rd declension i-stem) forms its ablative singular as igne or igni. Which ablative singular form of nox is correct, and why does nox NOT allow an -i ablative ending the way ignis sometimes does?

  1. The ablative singular of nox is noctem, using the accusative ending -em, because feminine nouns in the 3rd declension frequently syncretize the ablative and accusative singular forms when the stem ends in a stop consonant.
  2. The ablative singular of nox is nocti, using -i because all 3rd-declension feminine nouns take the -i ablative ending by gender convention, just as ignis does, since both nouns share the same case system.
  3. The ablative singular of nox is noctis, using the genitive singular ending, because feminine nouns of the 3rd declension use the genitive form in place of the ablative singular to avoid ambiguity with masculine nouns.
  4. The ablative singular of nox is nocte, using the consonant-stem ending -e. Unlike ignis, which is an i-stem noun retaining an optional -i ablative, nox is a pure consonant-stem noun and therefore takes only -e in the ablative singular. (correct answer)
Explanation: When navigating 3rd-declension nouns in Latin, the single most important question to ask is: is this an i-stem or a consonant-stem noun? That distinction controls several endings, including the ablative singular. Pure consonant-stem nouns — those whose stems end in a consonant without meeting the special i-stem criteria — take -e in the ablative singular. I-stem nouns, by contrast, can take -i (or optionally -e, as with ignis). Nox, noctis has the stem noct-, a pure consonant stem ending in a stop (-ct). It meets none of the i-stem criteria (it isn't a parisyllabic noun, nor does its stem end in two consonants preceded by a short syllable in the i-stem pattern). Therefore, its ablative singular is nocte — making D correct. A is wrong because noctem is the accusative singular, not the ablative. There is no syncretism of accusative and ablative singular in Latin 3rd declension; these are distinct forms with distinct endings. B is wrong because gender does not determine i-stem status. Being feminine doesn't entitle nox to an -i ablative. I-stem membership depends on stem formation, not grammatical gender. C is wrong because the ablative and genitive singular are never interchangeable in Latin grammar. Noctis is the genitive, and using it as an ablative would be a case error, not a legitimate convention. Study tip: Memorize the i-stem checklist (parisyllabic, or stem ending in two consonants). If a noun doesn't qualify, default to -e for the ablative singular — no exceptions.

Question 4

A student encounters the form civium and must determine its case, number, and the noun it comes from. She knows that civis, civis (m./f., citizen) is a 3rd-declension i-stem noun. Which analysis of civium is correct?

  1. civium is the accusative plural of civis, formed by adding -ium to the stem civ-, because i-stem masculine and feminine nouns use -ium in the accusative plural instead of the -es ending found in consonant-stem nouns.
  2. civium is the dative singular of civis, formed by adding -ium to the stem civ-, because i-stem nouns replace the standard dative singular ending -i with -ium to mark their i-stem classification.
  3. civium is the ablative plural of civis, formed by adding -ium to the stem civ-, because i-stem nouns use -ium for the ablative plural and -ibus for the dative plural to distinguish the two cases.
  4. civium is the genitive plural of civis, formed by adding -ium to the stem civ-. I-stem nouns use -ium rather than -um in the genitive plural, which is a primary marker distinguishing i-stems from consonant-stem nouns. (correct answer)
Explanation: When analyzing an unfamiliar Latin noun form, your first move should be to identify the noun's declension class and then match the ending against the paradigm. For 3rd-declension nouns, the critical distinction is whether a noun is a consonant-stem or an i-stem, because i-stems differ from consonant-stems in a few specific endings — and the genitive plural is the most important one. Civis is a classic i-stem noun (parisyllabic: equal syllables in nominative and genitive singular). In the full paradigm, the genitive plural of i-stem masculines and feminines ends in -ium rather than the consonant-stem -um. So civ- (the stem) + -ium = civium, genitive plural meaning "of the citizens." Answer D is correct. Answer A is wrong because the accusative plural of i-stem masculine/feminine nouns actually ends in -ēs (same as consonant-stems) — there is no -ium accusative plural for this subgroup. Answer B is entirely fabricated: there is no such thing as a dative singular ending -ium in any 3rd-declension noun. The dative singular of civis is cīvī. Answer C confuses the ablative plural with the genitive plural. The ablative plural of i-stem nouns ends in -ibus (e.g., civibus), not -ium. A reliable memory tip: for 3rd-declension i-stems, the genitive plural -ium is the signature marker. If you memorize that one ending, you can immediately identify forms like civium, partium, or hostium as genitive plural — a distinction Latin-2 exams test repeatedly.

Question 5

A student reads: Senatus populusque Romanus leges iustas dedit. She identifies leges as the direct object and looks up the noun: lex, legis (f., law, 3rd declension, stem leg-).

The student must confirm the case and number of leges in this sentence. She knows that leges can represent more than one case. After applying syntactic reasoning to the sentence, which analysis is correct, and what additional form would be identical to leges in a different syntactic role?

  1. leges here is the genitive singular of lex, because feminine nouns in the 3rd declension use the -es ending in the genitive singular, and the sentence means 'the senate gave of just law' in a partitive sense.
  2. leges here is the nominative plural (subject of dedit), formed by adding -es to stem leg-. The accusative plural is legum, formed by adding -um to the stem, so the two cases are distinct in form and there is no ambiguity.
  3. leges here is the accusative plural (direct object of dedit), formed by adding -es to stem leg-. The nominative plural is also leges (same form), so leges could appear as a subject in a different sentence with identical form but different syntactic function. (correct answer)
  4. leges here is the dative plural (indirect object of dedit), formed by adding -es to the stem leg-, and the ablative plural also takes -es in 3rd-declension feminine nouns, making dative and ablative plural identical to nominative and accusative plural.
Explanation: When analyzing a Latin noun's case, always use two tools together: the paradigm (what forms are possible for that ending?) and syntax (what role does the word play in the sentence?). The ending -es in 3rd-declension nouns is a classic ambiguity point, so both tools are essential. In Senatus populusque Romanus leges iustas dedit, the verb dedit ("gave") is transitive and already has a clear subject — Senatus populusque Romanus (nominative). That means leges must be filling a different role. Because dedit takes a direct object and no other noun is available to serve that function, leges is the accusative plural, modified by iustas (also accusative plural feminine, confirming agreement). Answer C is correct. Crucially, C also correctly notes that the nominative plural of lex is also leges — both cases share the -es ending in 3rd declension, meaning you genuinely cannot distinguish them without syntax. Answer A is wrong on two counts: -es is never the genitive singular ending in the 3rd declension (genitive singular is legis), and "gave of just law" is not grammatically coherent here. Answer B correctly identifies the nominative plural form but misidentifies leges as the subject (the subject is already Senatus populusque Romanus) and wrongly claims the accusative plural is legum — legum is actually the genitive plural. Answer D is simply fabricated; the dative and ablative plural of lex are legibus, not -es. As a study habit, whenever you see -es on a 3rd-declension noun, flag it immediately: ask yourself whether the sentence already has a subject before deciding if the word is nominative or accusative.

Question 6

A student must decline caput, capitis (n., head, 3rd declension, stem capit-) in the nominative, accusative, and vocative plural. She remembers the rule for neuter nouns but is unsure whether the plural endings differ from those of masculine/feminine 3rd-declension nouns. Which set of forms is entirely correct for all three cases in the plural?

  1. Nominative plural: capites; Accusative plural: capita; Vocative plural: capites — neuter nouns use -es in the nominative and vocative plural (following the pattern of consonant stems) but retain -a only in the accusative plural as a marker of the direct object.
  2. Nominative plural: capita; Accusative plural: capites; Vocative plural: capita — the accusative plural takes -es (as in masculine/feminine nouns) while nominative and vocative share the neuter -a ending, because accusative plural in neuter nouns follows the masculine pattern.
  3. Nominative plural: capita; Accusative plural: capita; Vocative plural: capita — all three cases share the ending -a added to the stem capit-, following the neuter rule that nominative, accusative, and vocative plural are always identical and end in -a. (correct answer)
  4. Nominative plural: capita; Accusative plural: capitum; Vocative plural: capita — the accusative plural uses the genitive plural ending -um added to the stem, because neuter nouns in the 3rd declension do not distinguish accusative from genitive in the plural.
Explanation: When declining neuter nouns in Latin, the single most important rule to internalize is this: in neuter nouns of any declension, the nominative, accusative, and vocative are always identical — and in the plural, they always end in -a. This rule applies universally, from 2nd-declension neuters like bellum (plural: bella) to 3rd-declension neuters like caput. For caput, the stem is capit-. Adding the neuter plural ending -a gives you capita across all three cases: nominative plural capita, accusative plural capita, vocative plural capita. This makes choice C correct. There is no variation among these three cases — Latin enforces this symmetry strictly for all neuter nouns. Choice A is a trap built on a false analogy: it borrows -es, the masculine/feminine 3rd-declension plural ending, for the nominative and vocative, then oddly reserves -a only for the accusative. Neuter nouns never take -es in any of these three cases. Choice B makes the opposite error, assigning -es to the accusative while correctly using -a for nominative and vocative — but the accusative plural of a neuter is never -es. Choice D confuses the accusative plural with the genitive plural; -um (or -ium) is the genitive plural ending, not the accusative, and conflating these two cases is a classic declension mix-up. Your study tip: memorize the neuter rule as a mantra — "Nom = Acc = Voc in neuter, and plural ends in -a." If you see -es attached to a neuter noun in any of these cases, that's always wrong.

Question 7

Examine the following partial declension chart for corpus, corporis (n., body, 3rd declension, stem corpor-):

  • Nominative singular: corpus
  • Genitive singular: corporis
  • Dative singular: corpori
  • Accusative singular: corpus
  • Ablative singular: corpore
  • Nominative plural: corpora
  • Genitive plural: corporum

A student notices that the nominative singular and accusative singular of corpus are identical (corpus). She then attempts to complete the remaining plural forms. Which of the following correctly lists the dative plural and ablative plural forms of corpus?

  1. Both the dative plural and ablative plural are corporibus, formed by adding -ibus to the stem corpor-, with no distinction between the two cases in the plural. (correct answer)
  2. The dative plural is corporis and the ablative plural is corpore, simply reusing the singular genitive and ablative forms to serve double duty in the plural, as neuter nouns do.
  3. The dative plural is corporium and the ablative plural is corporibus, because neuter nouns use -ium in the dative plural and -ibus in the ablative plural to distinguish the two cases.
  4. The dative plural is corporum and the ablative plural is corporibus, because -um marks the dative plural for all 3rd-declension nouns and -ibus marks the ablative plural exclusively.
Explanation: When you encounter a Latin declension question, your first move should be to identify the declension family and recall its endings pattern — especially for cases that look identical across two different slots. In the 3rd declension, both the dative plural and ablative plural share the same ending: -ibus, attached directly to the stem. For corpus, the stem is corpor-, so both the dative plural and ablative plural are corporibus. This sharing of a single form across two cases is a normal, systematic feature of Latin — not an error or shortcut. Answer A correctly captures this: one form, corporibus, serves both functions, and context (or syntax) tells you which case is intended. Answer B is wrong because it confuses singular and plural paradigms entirely. Corporis is the genitive singular and corpore is the ablative singular — neither reappears to "cover" plural cases. Latin doesn't recycle singular forms for plural slots. Answer C invents a false distinction. The ending -ium belongs to the genitive plural of certain 3rd-declension nouns (i-stems), not the dative plural. Mixing up -ium (genitive plural) with dative plural is a very common error — watch for it. Answer D misidentifies -um as a dative plural marker. In reality, -um or -ium marks the genitive plural, never the dative. Assigning corporum (which you already know is the genitive plural from the chart) to the dative slot contradicts information given right in the passage. Study tip: Memorize that in the 3rd declension, dative and ablative plural always share -ibus — just as 1st/2nd declension share -is. One suffix, two cases, context decides.

Question 8

A student is given two nouns to decline: pax, pacis (f., peace, 3rd declension, stem pac-) and navis, navis (f., ship, 3rd declension i-stem, stem nav-). She must write the ablative singular of each.

The student writes pace for the ablative singular of pax and navi for the ablative singular of navis. Her instructor marks one answer correct and one partially correct. Which statement best explains the evaluation?

  1. pace is fully correct for the consonant-stem noun, and navi is fully incorrect because i-stem feminine nouns always use -e in the ablative singular, following the same rule as consonant-stem nouns, making nave the only acceptable form.
  2. pace is fully correct because pax is a consonant-stem noun taking -e in the ablative singular. navi is partially correct: i-stem nouns like navis may take either -i or -e (nave) in the ablative singular, so navi is acceptable but nave is also a valid classical form. (correct answer)
  3. pace is partially correct because consonant-stem nouns like pax allow both -e and -i in the ablative singular, and navi is fully correct because i-stem nouns exclusively use -i in the ablative singular with no alternative form permitted.
  4. Both pace and navi are fully correct without qualification, because 3rd-declension feminine nouns uniformly use -e for consonant stems and -i for i-stems in the ablative singular, and neither form has any alternative or overlap.
Explanation: When declining 3rd-declension Latin nouns, one of the trickiest spots is the ablative singular, because the ending depends on whether the noun is a consonant stem or an i-stem. This distinction is exactly what the question is testing. Here's the rule: consonant-stem nouns (pax, pacis) take -e in the ablative singular — so pace is the one and only correct form, no ambiguity. I-stem nouns, however, are more flexible. Nouns like navis, navis can take either -i (navi) or -e (nave) in the ablative singular. Both are attested in classical Latin, making this a genuine two-form situation. So the student's navi is acceptable — but calling it "fully correct" without acknowledging nave overstates the case, which is why the instructor marks it only partially correct. Answer B captures this perfectly: pace earns full marks for the consonant-stem, while navi earns partial credit because nave is equally valid. Answer A is wrong because it claims i-stem feminines only use -e, which reverses the reality — navi is actually the more distinctively i-stem form, and both endings are valid. Answer C is wrong in the opposite direction: it incorrectly gives consonant-stems like pax a dual ending, when pace alone is correct for those nouns. Answer D is wrong because it denies any overlap or ambiguity, ignoring that i-stem ablatives genuinely allow two forms. A useful study tip: memorize that i-stems have wiggle room in the ablative singular (-i or -e), while pure consonant stems do not — they take only -e. Flag i-stem nouns in your vocabulary lists so you never forget their special behavior.

Question 9

A student is given the dictionary entry homo, hominis (m., human being, 3rd declension) and asked to produce all six cases in the plural only.

The student correctly writes the nominative plural as homines and the genitive plural as hominum. She then hesitates on the accusative plural. Which form is correct, and what reasoning distinguishes it from the nominative plural form homines?

  1. The accusative plural is also homines, formed by adding -es to the stem homin-. In the 3rd declension, nominative and accusative plural are identical for masculine and feminine nouns, so no distinction in form exists between these two cases in the plural. (correct answer)
  2. The accusative plural is hominum, formed by adding -um to the stem homin-, the same ending as the genitive plural. Masculine nouns in the 3rd declension use -um for both genitive and accusative plural to signal definiteness.
  3. The accusative plural is hominibus, the same form shared by the dative and ablative plural. Latin regularly syncretizes the accusative with the dative/ablative plural in the 3rd declension for masculine nouns to reduce ambiguity.
  4. The accusative plural is homina, formed by replacing the nominative plural ending -es with the neuter plural ending -a, because accusative plurals of masculine nouns in the 3rd declension borrow neuter endings when the stem ends in a nasal consonant.
Explanation: When tackling 3rd declension plural endings, you need to memorize the full case ending chart rather than assuming each case looks unique. A critical insight for masculine and feminine nouns specifically: the nominative and accusative plural share the same form. For homo, hominis, the stem is homin-. You attach -es to get both the nominative plural (homines, "human beings" as subject) and the accusative plural (homines, "human beings" as direct object). The cases are distinguished entirely by context and syntax, not by spelling. Answer A is correct for exactly this reason — there is no formal difference between these two plural forms for masculine and feminine 3rd declension nouns. Answer B is wrong on two counts: hominum is the genitive plural (stem + -um), not the accusative, and Latin has no grammatical concept of "definiteness" — that's a feature of languages like English or Greek, not classical Latin. Answer C incorrectly identifies hominibus as the accusative plural; hominibus is real, but it serves the dative and ablative plural, not the accusative. Answer D invents a false rule — masculine nouns never borrow neuter plural endings (-a) for their accusative, and nasal stems have no special accusative behavior. This is a classic distractor that sounds technical but describes nothing real. A reliable study tip: memorize the 3rd declension plural chart as a unit — -es, -ium/-um, -ibus, -es, -ibus (nominative through ablative). Noticing that nominative and accusative are both -es for masculines/feminines will save you from hesitating exactly the way this student did.

Question 10

A student is constructing the sentence: 'The consul spoke to the citizens about the dangers.' She identifies the relevant nouns as consul, consulis (m., 3rd declension, stem consul-), civis, civis (m., citizen, i-stem, stem civ-), and periculum, -i (n., danger, 2nd declension). She must use civis in the dative plural (indirect object) and periculum in the ablative plural (with de, about).

The student writes civibus for the dative plural of civis and periculis for the ablative plural of periculum. Which evaluation of her work is accurate, and what is the key morphological difference between how these two nouns form their dative/ablative plurals?

  1. Both forms are correct, and the endings -ibus and -is are interchangeable across declensions, since both signal the dative and ablative plural equally in classical Latin regardless of which declension a noun belongs to.
  2. Both forms are correct. 3rd-declension nouns use -ibus for the dative and ablative plural (civ- + ibus = civibus), while 2nd-declension nouns use -is for the same cases (pericul- + is = periculis). The endings differ by declension and are not interchangeable. (correct answer)
  3. civibus is correct for the dative plural, but periculis is incorrect; the ablative plural of 2nd-declension periculum should be periculibus, since all Latin nouns use the ending -ibus for the ablative plural regardless of declension.
  4. civibus is incorrect because i-stem nouns like civis use -ium rather than -ibus in the dative plural, giving civium. periculis is correct for the 2nd-declension dative and ablative plural using the ending -is.
Explanation: When working with Latin noun endings, your first instinct should be to identify the declension of each noun, because different declensions follow different paradigms — endings that look similar can signal very different things depending on which declension you're in. For the dative and ablative plural specifically, the pattern breaks down cleanly: 3rd-declension nouns (including i-stems like civis) use -ibus, while 2nd-declension nouns like periculum use -is. Applying this: civ- + -ibus = civibus ✓, and pericul- + -is = periculis ✓. Both of the student's forms are correct, which makes B the right answer — and crucially, B also correctly explains why the endings differ, tying each form to its declension. A is tempting because it also calls both forms correct, but it contains a dangerous misconception: -ibus and -is are absolutely not interchangeable across declensions. Each ending belongs to a specific paradigm. Swapping them produces ungrammatical Latin. C incorrectly claims that all Latin nouns take -ibus in the ablative plural. This overgeneralizes the 3rd-declension rule and would produce the nonexistent form periculibus for a 2nd-declension noun. D confuses the dative/ablative plural ending -ibus with the genitive plural ending -ium, which is where i-stems do show their special character. Civium is the genitive plural of civis, not the dative. Study tip: When drilling noun endings, always tag each form with its case, number, and declension. The dative/ablative plural is a classic spot where declension distinctions get tested — know your -is vs. -ibus split cold.