from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The word or words serving to define another word or expression, as in a dictionary entry.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The word or phrase that defines the definiendum in a definition.
Latin dēfīniēns, present participle of dēfīnīre, to define; see define.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin, substantive use of dēfīniēns ("[a] defining"), present active participle of dēfīniō ("I set bounds to”, “I define"). (Wiktionary)