Latin adjectives change form to match the nouns they describe, so students need a clear reference for endings, gender, number, and case. This cheat sheet covers 1st/2nd declension adjectives, 3rd declension adjectives, agreement rules, and common exceptions. It helps students choose the correct adjective form when reading, translating, or composing Latin sentences.
The most important rule is that adjectives agree with nouns in gender, number, and case, but not necessarily in declension. 1st/2nd declension adjectives use -us, -a, -um patterns, while many 3rd declension adjectives use i-stem endings. Comparative adjectives usually follow 3rd declension patterns, and a few common adjectives have irregular forms that must be memorized.
Key Facts
- An adjective must agree with its noun in gender, number, and case.
- A 1st/2nd declension adjective like bonus, bona, bonum uses masculine 2nd declension, feminine 1st declension, and neuter 2nd declension endings.
- The nominative singular forms of many 1st/2nd declension adjectives are masculine -us, feminine -a, and neuter -um.
- A 3rd declension adjective such as fortis, forte usually uses one form for masculine and feminine and a separate neuter form.
- Neuter nominative and accusative forms are always the same in the same number.
- The neuter plural nominative and accusative ending is usually -a, as in bona or fortia.
- Many 3rd declension adjectives use genitive plural -ium and neuter plural -ia.
- Comparative adjectives such as fortior, fortius are declined mostly like 3rd declension consonant-stem adjectives.
Vocabulary
- Adjective
- A word that describes a noun and changes form in Latin to show gender, number, and case.
- Agreement
- The rule that an adjective must match its noun in gender, number, and case.
- 1st/2nd Declension Adjective
- An adjective that uses 1st declension endings for feminine forms and 2nd declension endings for masculine and neuter forms.
- 3rd Declension Adjective
- An adjective that uses 3rd declension endings and often has i-stem forms such as genitive plural -ium.
- Comparative Adjective
- An adjective form meaning more or rather, often ending in -ior for masculine and feminine and -ius for neuter.
- Neuter Rule
- The rule that neuter nominative and accusative forms are identical, and neuter plural nominative and accusative usually end in -a.
Common Mistakes to Avoid
- Matching the adjective to the noun's declension is wrong because adjectives agree in gender, number, and case, not declension.
- Using the masculine form for every noun is wrong because Latin adjectives must change for feminine and neuter nouns as well.
- Forgetting that neuter nominative and accusative are identical is wrong because neuter nouns and adjectives follow this rule in every declension.
- Using 1st/2nd declension endings on all adjectives is wrong because 3rd declension adjectives have different endings such as -is, -e, -ium, and -ia.
- Assuming word order proves agreement is wrong because Latin word order is flexible, so endings show which adjective describes which noun.
Practice Questions
- 1 Choose the correct form of bonus, bona, bonum to agree with puella, nominative singular: bonus, bona, or bonum.
- 2 Choose the correct form of fortis, forte to agree with bellum, accusative singular: fortem, fortis, or forte.
- 3 Make magnus, magna, magnum agree with servorum, genitive plural masculine.
- 4 Explain why magna can describe both puella nominative singular and bella nominative plural neuter, even though the forms look the same.