Subject complement

In traditional grammar, a subject complement is a predicative expression that follows a copula (commonly known as a linking verb), which complements the subject of a clause by means of characterization that completes the meaning of the subject.^[1]

When a noun, noun phrase, or pronoun functions as a subject complement, it is called a predicative nominal. When an adjective or analogous phrase functions as subject complement, it is called a predicative adjective. In either case the predicative complement corresponds to the subject.

Within the small class of copulas that preface a subject complement, the verb be, or one of its concomitant forms, is the most common. Because a copula is an intransitive verb, subject complements are not customarily construed to be the object of the verb. They are often deemed to be neither arguments nor adjuncts of a predicate. A plural or singular subject, rather than a subject complement determines the grammatical number expressed by a copula.^[2][3]