headword

head·word  (hdwûrd)

n.

1. A word, phrase, or name, usually set in boldface or other distinctive type, that serves as the heading for an entry in a dictionary, encyclopedia, or similar reference work. Also called entry word.

2. Grammar A word that may be modified by an adjunct.

Thesaurus

Noun	1.	headword - a content word that can be qualified by a modifier head word content word, open-class word - a word to which an independent meaning can be assigned phrase - an expression consisting of one or more words forming a grammatical constituent of a sentence
	2.	headword - a word placed at the beginning of a line or paragraph (as in a dictionary entry) word - a unit of language that native speakers can identify; "words are the blocks from which sentences are made"; "he hardly said ten words all morning" dictionary entry, lexical entry - the entry in a dictionary of information about a word