1.noun(grammar) An element of the predicate of a sentence which supplements the subject or object by means of the verb. Predicatives may be nominal or adjectival.
2.noun(grammar) In some languages, a special part of speech used as a predicate and denoting a state of being.
3.adjective(grammar, of an adjectival or nominal phrase) Modifying a noun while in a predicate phrase, which predicate phrase is other than the noun phrase and occurs after a verb, as a predicate; contrasted with attributive.
"In the sentence, ‘This house is big’, ‘big’ is predicative, whereas in ‘This is a big house’, it is attributive."