An antecedent is something that comes before something else. (Ante= before.)
In grammar, you decide whether to use a plural or singular verbs and possessives based on the antecedent. In the sentence "The boys took their books", "boys" is the antecedent that triggers "their" instead of "his".
An antecedent refers to a prior event or circumstance that precedes or influences another event. In linguistics, an antecedent is a word, phrase, or clause to which a pronoun refers. Identifying the antecedent is important for understanding the meaning and context of a sentence.