X-bar
Origin
Pronunciation of its text representation: a letter X with overbar.
Noun
noun
- (grammar, X-bar theory) A phrase, or, equivalently, a node in a syntax tree, which consists either of: (1) an adjunct and another X-bar phrase, (2) a head, X, and an optional complement, or (3) a conjunction sandwiched between two other X-bars. The X is a "pro-letter" which can be substituted by letters such as N for noun, V for verb, P for preposition, I for inflectional, etc.
- 1988, Andrew Radford, Transformational grammar: a first course Chapter 7, For example, the fact that give must occur as the leftmost constituent of the V-bar containing it follows from two conditions. The first is a putatively universal linearisation (i.e. word-order) principle proposed by Stowell (1981, p. 68) which we might call the PERIPHERY PRINCIPLE: this can be outlined informally as in (33) below:
(33) PERIPHERY PRINCIPLE
(33) The head term of a Phrase appears at the periphery of X-bar
What (33) says is that the Head must be the leftmost or rightmost immediate constituent of X-bar.
Usage notes
An X-bar is denoted as
\bar{X}
, or more commonly, as
X'
.