Predicative adjectives constitute a class of words that predicate (declare) a property of a subject in a predicative construction.[1] The grammatical coding of predicative adjectives may be identical to or distinct from that of predicative intransitive verbs. If predicative adjectives are coded in an identical manner to predicative verbs, they are considered verbal. If they are treated differently, they are classified as non-verbal. Some languages display both types.

To determine whether a predicative adjective is coded in the same manner as intransitive verbs, the behavior of the two word classes should be examined by applying the following series of tests, in the exact order listed. If at any point the test determines that predicative adjectives are verbal or nonverbal, any remaining questions should be skipped.

1. Do verbal predicates show agreement with their nominal argument (in nominative languages, the subject)? [2] If no, continue to question 2. If yes, is the means of coding agreement the same for predicative adjectives and predicative verbs? [3] If no, continue to question 3. If yes, predicative adjectives are verbal.

2. Does the language have an explicit copula? If no, continue to question 3. If yes, is the same copula used in the same manner for predicative adjectives and predicative verbs? If so, predicative adjectives are verbal; if not, they are non-verbal.

3. Is negation expressed in the same manner for predicative adjectives and predicative verbs? If so, predicative adjectives are verbal; if not, they are non-verbal.

Types:

AdjPredV: Predicative adjectives are verbal.

AdjPredNonV: Predicative adjectives are non-verbal.

AdjPredMix: Predicative adjectives are verbal or non-verbal, with the distinction lexically determined.[4]

AdjPredMixSwitch: Predicative adjectives are verbal or non-verbal, with the distinction semantically determined.[5]

[1] Predicate adjectives appear with or without a copula in structures such as The house is big. They should not be confused with adnominal adjectives, which do not fulfill a predicative function (such as The big house or The big house is here). It is possible for predicative adjectives to exist in a language that does not have adnominal adjectives.

[2] Intransitive verbs should be examined in their most basic form (generally, present tense, declarative mood, the most neutral aspect). If agreement doesn’t exist, the language is considered to lack verbal predicate agreement, even if agreement can be found in other tenses.

[3] The answer is no if (a) only one of the two types of predicates shows agreement, or (b) both types display agreement but based on (at least partly) distinct grammatical categories.

[4] Some predicative adjectives are exclusively verbal, while others are exclusively non-verbal. If this value applies, the details should be specified in the commentary.

[5] For example, adjectives that express transitional features may belong to one type, while adjectives that express permanent features belong to the other. If this value applies, the details should be specified in the commentary.