A head is a constituent of an endocentric construction that, if standing alone, could perform the syntactic function of the whole construction.
It may govern the:
- agreement of grammatical categories, such as person and number, or
- occurrence of other constituents.
In the following construction, the noun chair heads the noun phrase. It also determines number on the verb:
In the following construction, the verb given heads the verb phrase would have given. It also determines the occurrence of a direct object and indirect object later in the clause: