Adjective agreement is the rule that a Latin adjective must match the noun it describes in gender, number, and case. Because Latin word order is flexible, matching endings (not position) tell you which adjective goes with which noun, which is essential for accurate translation on the AP Latin exam.
In Latin, an adjective doesn't just sit next to its noun the way English adjectives do. It locks onto its noun grammatically by agreeing in three things: gender (masculine, feminine, neuter), number (singular or plural), and case (nominative, genitive, dative, accusative, ablative, vocative). The adjective's specific ending signals all three at once, just like a noun's ending does. That's how Vergil can separate an adjective from its noun by half a line of hexameter and you can still pair them up.
Two details the CED stresses. First, adjectives exist in only the first three declensions, but they can modify nouns in any declension. So celer nauta (third-declension adjective, first-declension noun) is perfectly fine, and the endings will not look alike. Agreement means matching gender, number, and case, not matching letters. Second, an adjective can modify an implied noun. When it does, it's being used substantively, standing in as a noun itself (boni, "the good men"). Vergil does this constantly, so you can't translate his adjectives without spotting what they agree with, stated or not.
Adjective agreement is "repeated for review" knowledge in the AP Latin CED, which means the exam assumes you've mastered it and tests it constantly. It sits directly under AP Latin 4.2.C (Topic 4.2, Vergil Aeneid Book 1) and AP Latin 5.1.E (Topic 5.1, Aeneid Book 4, the Dido passages). Both objectives ask you to describe how adjectives function in context and contribute to meaning. Agreement is also the hidden engine behind translation objectives 4.2.D and 5.1.F. If you pair an adjective with the wrong noun, your literal translation falls apart, and the exam's translation rubric scores you segment by segment. In poetry, agreement does double duty as style. Vergil deliberately separates agreeing pairs to build word pictures and figures like chiasmus (4.2.F, 5.1.G), so reading the endings, not the word order, is how you see what he's doing.
Keep studying AP Latin Unit SL2Apodi9BqlvQoqDkdk
Comparative Adjective (Unit 4)
Comparative and superlative adjectives change degree, but they never stop agreeing. A superlative like pulcherrima still has to match its noun in gender, number, and case, so the agreement rule travels with the adjective through all three degrees.
Gerund and Gerundive (Unit 5)
The gerundive is an adjective formed from a verb, and the CED's own example shows why agreement matters here. In ad eas res conficiendas, conficiendas is feminine accusative plural because res is. Telling a gerundive (agrees with a noun) from a gerund (is a noun) usually comes down to checking agreement.
Ablative Absolute (Units 4-5)
An ablative absolute is built on agreement. The participle is a verbal adjective that must agree with its noun in the ablative, so spotting a matched ablative noun-participle pair is how you find the construction in the first place.
Chiasmus and Word Order (Units 4-5)
Vergil scrambles word order for effect, arranging pairs in a-b-b-a patterns. Agreement is what lets him get away with it. The endings tie each adjective to its noun no matter where they land in the line, so you read the grammar first and the artistry second.
Multiple-choice questions on both the required Vergil syllabus and sight passages routinely ask which noun a given adjective modifies, or what an adjective's case and number are. The matching ending is your evidence. On the free-response translation, agreement errors are translation errors. Render miserae Didoni as dative singular ("to/for unhappy Dido"), not as a plural or a subject, because the scoring works in small segments and each wrong pairing costs you. Agreement also feeds analysis questions. If you claim Vergil's word order creates a picture (an adjective embracing its noun across a line, say), you need the agreeing endings as your textual proof. No released FRQ names "adjective agreement" as a term, but nearly every translation segment quietly tests it.
Agreement does not mean the adjective and noun have identical endings. Acer poeta shows a third-declension adjective agreeing with a first-declension noun; both are masculine nominative singular, but the endings look nothing alike. Adjectives come only from the first three declensions yet modify nouns in any declension, so check gender, number, and case, never the spelling of the ending.
A Latin adjective must agree with its noun in gender, number, and case, and the adjective's ending signals all three.
Agreement does not mean identical endings, because an adjective from one declension can modify a noun from any declension.
An adjective with no stated noun is used substantively and acts as a noun itself, like boni meaning "the good men."
In Vergil, word order won't tell you which adjective goes with which noun; the endings will, even across a whole line.
Gerundives and participles are verbal adjectives, so they follow the same agreement rule, which is how you identify constructions like the ablative absolute.
On the translation FRQ, pairing an adjective with the wrong noun counts as a translation error in that segment.
It's the rule that an adjective must match the noun it describes in gender, number, and case. The adjective's ending encodes all three, which is how you pair adjectives with nouns in Vergil's flexible word order.
No. Adjectives occur only in the first three declensions but can modify nouns in any declension. A third-declension adjective like celer can modify a first-declension noun like nauta, with totally different-looking endings.
No, and in Vergil it often doesn't. Poets separate agreeing pairs for emphasis and patterns like chiasmus, so you find the noun by matching gender, number, and case, not by position in the line.
A regular adjective modifies a stated noun (magnus vir, "the great man"). A substantive adjective modifies an implied noun and works as a noun on its own, so magni alone can mean "the great men." The ending tells you the gender and number of the implied noun.
Yes, constantly. It's "repeated for review" knowledge under objectives 4.2.C and 5.1.E, MCQs ask which noun an adjective modifies, and the translation FRQ penalizes any segment where you pair an adjective with the wrong noun.