complement:

This is a term used to denote a specific grammatical function. A complement is an expression which is directly merged with a head word, thereby projecting the head into a larger structure of essentially the same kind. In ‘close the door’, the door is the complement of the verb close; in ‘after dinner’, dinner is the complement of the preposition after; in ‘good at physics’, at physics is the complement of the adjective good; in ‘loss of face’, of face is the complement of the noun loss. As these examples illustrate, complements typically follow their heads in English. Thus, a complement has a close morphological, syntactic and semantic relation to its head.

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