A phrase is a sequence of words that function together as a unit within a sentence. A phrases forms a constituent.


1   Form

The form of a phrase is given by three projection rules, which together are called the spine of a phrase:

  1. XP -> (YP) X' or XP -> X' (YP) (Specifier rule)
  2. X' -> (ZP) X' or X' -> X' (ZP) (Adjunct rule)
  3. X' -> (WP) X or X' -> X (WP) (Complement rule)


The head of a phrase has the following properties:

2   Example


3   Properties

Phrases are endocentric and headed; every phrase has a head, a prominent word that gives the phrase its category, and every phrase has the same function as its head. Words in a phrase that are not the head are called non-head material or dependents. Non-head material is optional and phrasal (i.e. it must be a phrase).

3.1   Structural properties

As siblings to heads, complements are strictly closer to the head than adjuncts.

book [of poems] [with a red cover]

* book [with a red cover] [of poems]

Since the complement rule not recursive, phrases have exactly one complement.

* the book of poems of fiction

Since the adjunct rule is recursive, a phrase can have many adjuncts.

Adjuncts can be reordered.

Alice gave Bill an apple at school yesterday

Alice gave Bill an apple yesterday at school

Since the specifier rule is not recursive, phrases have exactly one specifier, except with conjunction.

two or three books

* two three books

Specifiers must appear farthest from the head:

* boring the book

4   Classification

Adjuncts and complements are of different types, so we can not use them with a conjunction.

the book of poems with a red cover and with a blue spine

the book of poems and of fiction from Black

* the book of poems and from Blackwell

Complement / adjunct distinct clearly holds for modifiers that appear predominantly as well.

Note, with X-bar theory, we parse "the German teacher" correctly as either "the person who teaches German" or "the German person who teaches" by distinguishing between "German" is a complement or adjunct. Note when we add an adjunct indicating a place of origin, then the NP is no longer ambiguous: "the French German" teacher.

4.1   Phrasal categories

4.1.2   Voice Phrase

There is to recognize a voice phrase; or at least, there is no way of telling a voice phrase apart from a verb phrase.

Voice = v ("little v") = V_voice

5   History

The first presentation of X-bar theory appear in Chomsky (1970).

Jackendoff's seminal book X-bar Theory (1975) is the source of many ideas surrounding X-bar theory.

6   Notes

[*]Specifiers only appear in noun phrases.

7   Further reading