/ Dictionary / Index T trillium: Meaning and Definition of Find definitions for: tril•li•um Pronunciation: (tril'ē-um), [key] — n. any of several plants belonging to the genus Trillium, of the lily family, having a whorl of three leaves from the center of which rises a solitary, three-petalled flower. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: trillium (Thesaurus) trillion trilobate Related Content Daily Word Quiz: blithesome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language