Specifier

In X-bar theory in linguistics, specifiers, head words, complements and adjuncts together form phrases. Specifiers differ from complements and adjuncts because they are non-recursive, as you can only have one specifier. They are not sisters of the head, but rather sisters of the phrase formed by the head and the complement or adjunct. In English, some example of specifiers are determiners such as the, a, this, quantifiers such as no, some, every, and possessives such as John’s and my mother’s, which can precede noun phrases. Verb phrases can be preceded by quantifiers such as each, and all. Adjective phrases and adverbial phrases can be preceded by degree words such as very, extremely, rather and quite.