/ Dictionary / Index L loony: Meaning and Definition of Find definitions for: loon•y Pronunciation: (l'nē), [key] — adj., n., pl. loon•i•er, loon•i•est, loon•ies. —adj. lunatic; insane. extremely or senselessly foolish. —n. a lunatic. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: loony (Thesaurus) looney loony bin Related Content Daily Word Quiz: aversion Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language