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, and phrases 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 technical syntax terminology, specifier is a YP that is the sister of X′, and the daughter of XP. The rule is XP → X′, where YP is the specifier. The X-bar schema of this phrase structure can be seen in the tree diagram below : In recent transformational grammar, the term specifier is not normally used to refer toa 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 is said to occupy the specifier of a head X.
Semantic definition of specifier
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. 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 specifies novels in this noun phrase
She is - quite specifies certain of success in the adverbial phrasequite certain of success
Different form classes can occupy a specifier position, typically determiners and possessors in noun phrases, and an auxiliary verb in a verb phrase.
is a Wh-movement landing site. Wh-movement is moving the smallest XPwh to available CP specifier position and XPwh mean question word or wh-. Wh-movement could raise XPwh to but it only moves under Subjacency Condition, that means if it violates Subjacency Condition then it will stop raising XPwh. Example: a) Lucy loves . b) does Lucy love ___? , become and a wh-word has to be moving to . |352x352px
Spec,TP
is Extended Projection Principle landing site. EPP moves the subject DP from to when the sentence is tensed. Note that the subject is in in most sentences but can have an object. Example: a) will eat the sandwich ] ]. File:Lucy_will_eat_sandwich.png|none|thumb|"Lucy will eat sandwich." "will" is the tense word in this sentence and it fulfill EPP. Thus, moved from to . b) make eat the sandwich ] ] ] ]. File:I_make_Lucy_eats_sandwich.png|none|thumb|304x304px|"I make Lucy eats sandwich." moved from to and moved from to . here is not the subject of the sentence and it is the Direct-Object in the sentence.
Spec,DP
In determiner phrase, possessive phrase DP is at DP specifier position the and possessive -'s is a determiner of the DP complement. Example: a) b) 's destruction] From these two examples, we can see that specifies in example b). In contrast, example a) do not have any specifier but it has Preposition Phrase as NP complement.
