Found:

head

SYNTAX: See X-bar theory.

MORPHOLOGY: notion introduced in morphology by Williams (1981a) to account for the fact that a complex word shares most, if not all, properties with one of its constituents. The constituent that determines the properties of the complex word as a whole is called the head of that word. The head of a word is either the rightmost or the leftmost morpheme of a word. This generalization lies at the heart of the so-called Righthand Head Rule. EXAMPLE: the English word withstand is a strong verb just like stand. Hence, stand is the head of the complex word withstand. Also see relativized head, and Relativized Righthand Head Rule.

LIT.	Di Sciullo, A. M. and E. Williams (1987) Spencer, A. (1991) Williams, E. (1981a)