/ Dictionary / Index T trilby: Meaning and Definition of Find definitions for: tril•by Pronunciation: (tril'bē), [key] — pl. -bies. a hat of soft felt with an indented crown. Also called tril&prim;by hat&prim;. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: trilby (Thesaurus) trilateration trilemma Related Content Daily Word Quiz: benevolent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language