Complement (linguistics)
In grammar the term complement is used with different meanings. The primary meaning is a word, phrase or clause which is necessary in a sentence to complete its meaning. We find complements which function as a sentence element (i.e. of equal status to subjects and objects) and complements which exist within sentence elements.
Subject complements
A subject complement tells more about the subject by means of the verb. In the examples below the sentence elements are (SUBJECT + VERB + COMPLEMENT)
Mr is a management consultant. (a predicative nominative)
She looks ill. (a predicative adjective)
Object complements
An object complement tells us more about the object by means of the verb. In the examples below the sentence elements are (SUBJECT + VERB + OBJECT + COMPLEMENT). Object complements can often be removed leaving a well-formed sentence, thus the use of the term complement is slightly illogical.
We elected him chairman. (a predicative nominative)
We painted the house red. (a predicative adjective)
Adverbials as complements
Adverbials, central to the meaning of a sentence, are usually adjuncts (i.e. they can be removed and a well-formed sentence remains). If, however, an adverbial is a necessary sentence element, then it is an adverbial complement. Adverbial complements often occur with a form of the copula be acting as a clause's main verb. The structure of the sentence below is (SUBJECT + VERB + ADVERBIAL COMPLEMENT)
John is in the garden.
Verb objects
Some grammarians refer to objects as complements.