In X-bar theory

X-bar theory

X-bar theory is a component of linguistic theory which attempts to identify syntactic features presumably common to all those human languages that fit in a presupposed framework...

 in linguistics

Linguistics

Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....

, specifiers, head words, and complement

Complement (linguistics)

In grammar the term complement is used with different meanings. The primary meaning is a word, phrase or clause that is necessary in a sentence to complete its meaning. We find complements that function as an argument and complements that exist within arguments.Both complements and modifiers add...

s together form phrases. Specifiers differ from complements because they are not sisters of the head, but rather sisters of the phrase formed by the head and the complement. In English, some example of specifiers are words such as the, no, some, every, John's and my mother's which can precede Noun phrase

Noun phrase

In grammar, a noun phrase, nominal phrase, or nominal group is a phrase based on a noun, pronoun, or other noun-like word optionally accompanied by modifiers such as adjectives....

s. Adverbial phrase

Adverbial phrase

An adverbial phrase is a linguistic term for a group of two or more words operating adverbially, when viewed in terms of their syntactic function.Compare the following sentences:*I'll go to bed soon.*I'll go to bed in an hour....

s can be preceded by degree words such as very, extremely, rather and quite.

These specifiers are so called because they further qualify the category of the head - in these examples nouns and adverbs - in the phrase.

For example:

• My friend likes [Jane Austen's novels] - Jane Austen's specifies novels in this noun phrase
• She is [quite certain of success] - quite specifies certain of success in the adverbial phrase quite certain of success

In recent transformational grammar

Transformational grammar

In linguistics, a transformational grammar or transformational-generative grammar is a generative grammar, especially of a natural language, that has been developed in the Chomskyan tradition of phrase structure grammars...

, the term specifier is not normally used to refer to a type of word or phrase, but rather to a structural position provided by X-bar theory or some derivative thereof. In this usage, a phrase (usually a full XP, though in bare phrase structure it could in theory be an intermediate category) is said to occupy the specifier (SpecXP for short) of a head X.

In technical syntax

Syntax

In linguistics, syntax is the study of the principles and rules for constructing phrases and sentences in natural languages....

 terminology, specifier is the sister of X′ in the X-bar

X-bar theory

X-bar theory is a component of linguistic theory which attempts to identify syntactic features presumably common to all those human languages that fit in a presupposed framework...

 schema of phrase structure

Phrase

In everyday speech, a phrase may refer to any group of words. In linguistics, a phrase is a group of words which form a constituent and so function as a single unit in the syntax of a sentence. A phrase is lower on the grammatical hierarchy than a clause....

 seen in the tree diagram

Parse tree

A concrete syntax tree or parse tree or parsing treeis an ordered, rooted tree that represents the syntactic structure of a string according to some formal grammar. In a parse tree, the interior nodes are labeled by non-terminals of the grammar, while the leaf nodes are labeled by terminals of the...

 below (where XP corresponds to X″):

Different form classes can occupy a specifier position, typically determiners

 and possessors

Possession (linguistics)

Possession, in the context of linguistics, is an asymmetric relationship between two constituents, the referent of one of which possesses the referent of the other ....

 in noun phrase

Noun phrase

In grammar, a noun phrase, nominal phrase, or nominal group is a phrase based on a noun, pronoun, or other noun-like word optionally accompanied by modifiers such as adjectives....

s (N″), and an auxiliary verb

Auxiliary verb

In linguistics, an auxiliary verb is a verb that gives further semantic or syntactic information about a main or full verb. In English, the extra meaning provided by an auxiliary verb alters the basic meaning of the main verb to make it have one or more of the following functions: passive voice,...

 in a verb phrase

Verb phrase

In linguistics, a verb phrase or VP is a syntactic unit composed of at least one verb and the dependents of that verb. One can distinguish between two types of VPs, finite VPs and non-finite VPs . While phrase structure grammars acknowledge both, dependency grammars reject the existence of a...

(V″).