First- and Second-Declension Adjectives

First- and second-declension adjectives use second-declension endings for the masculine and neuter, and first-declension endings for the feminine. Their dictionary form normally gives three nominatives: bonus, bona, bonum “good.” Those three forms reveal one adjective, not three separate words.

The label describes the adjective’s endings, not the declension of the noun it modifies. Bonus can agree with first-declension masculine agricola, bona with fifth-declension feminine rēs, and bonum with third-declension neuter nōmen. Agreement supplies gender, number, and case; the adjective supplies its own endings. Review that division of labor on Adjective Agreement.

The complete paradigm of bonus, bona, bonum

The neuter rule is visible twice: nominative, accusative, and vocative are identical, and their plural ends in -a. Long vowels distinguish forms such as feminine ablative singular bonā from nominative bona, and masculine accusative plural bonōs from accusative singular bonum.

One paradigm, nouns from any declension

Bonus is masculine nominative singular with medicus; aegrum is masculine accusative singular with puerum. All four happen to be second-declension forms, but that visual match is not the rule.

Feminine nominative bona agrees with fifth-declension rēs. Inventū is a supine in -ū in the (formal) construction “difficult to find”; it does not participate in the agreement.

Third-declension neuter nōmen takes neuter nominative novum and predicative grātum. Dative cīvibus belongs to grātus alicui, “welcome or pleasing to someone.”

Fourth-declension feminine accusative manum takes dextram; first-declension feminine ablative aquā takes frīgidā. The adjective forms are selected by features, not by copying -um or -ā from whatever noun is nearby.

Attributive and predicative uses

An attributive adjective forms part of a noun phrase. A predicative adjective states a property of the subject or object. Both decline in exactly the same way.

Both adjectives are attributive: masculine nominative parvus with subject canis, and masculine accusative magnum with object equum. Third-declension canis does not force a third-declension adjective.

Parvus, ācer, and impavidus are predicated of masculine nominative canis. Ācer belongs to the third declension, showing that coordinated predicates may come from different paradigms while sharing the same features.

Predicative bonum and magnum are neuter nominative singular. English puts “good” and “great” after verbs; Latin position is more flexible, but agreement remains compulsory.

Adjectives in -er: two stem patterns

Some masculine nominatives end in -er rather than -us. The remaining forms reveal whether the e belongs to the stem.

There is no dependable shortcut from the masculine nominative alone. Memorize all three citation forms. Quantity also matters: adjective līber means “free,” while noun liber, librī means “book.”

The adjective is pulcher with masculine hortus, but feminine would be pulchra via and neuter pulchrum templum. Forms such as ❌ pulchera are not Classical.

Nominative feminine singular lībera agrees with fēmina. The first accusative plural līberōs is substantival and means “children”; the second is predicative and means “free.” The wordplay is possible because the adjective and the noun līberī “children” overlap historically and morphologically.

Miser keeps e throughout: misera puella, miserum animal, miserī puerī. Do not remodel it on pulcher.

Position and semantic focus

The adjective may precede or follow its noun. There is no rigid rule equivalent to English “adjective before noun.” A preceding adjective often frames a quality as salient or expected; a following adjective can identify, contrast, or add weight. Context matters more than a mechanical formula.

The contrast licenses an adjective without a repeated noun: veterem is feminine accusative singular because understood epistulam supplies its features. Such substantival use grows naturally out of agreement.

An authentic maxim shows neuter plural adjectives used substantivally. It is reproduced in source spelling:

Omnia, praeclāra, and rāra are neuter nominative plural in grammatical analysis; the quotation itself remains unmacronized. The omitted verb sunt is easily supplied.

Boundaries and irregular members

The bonus pattern is productive, but not every adjective with familiar-looking nominatives is fully regular. Pronominal adjectives such as ūnus, tōtus, alius, and nūllus have genitive singular -īus and dative singular -ī. Possessive meus has masculine vocative mī. Bonus, malus, magnus, parvus, and multus decline regularly here but form comparison irregularly.

(Archaic) and (literary) poetry can preserve alternative endings or exploit separation and contraction. For neutral Classical prose, use the paradigm above; do not import rare poetic forms merely because a dictionary lists them.

Common Mistakes

1. Making the adjective copy a third-declension noun ending

2. Forgetting the neuter plural in -a

3. Keeping the e in pulcher forms

4. Dropping the e from miser

Key Takeaways

The bonus, bona, bonum class combines second-declension masculine and neuter endings with first-declension feminine endings. It can modify nouns of any declension. Learn -er adjectives by all three nominatives because some lose e and others retain it, and always choose the adjective form from gender, number, and case—not from the noun’s visible ending.