/ Dictionary / Index U usnea: Meaning and Definition of Find definitions for: us•ne•a Pronunciation: (us'nē-u), [key] — n. any pale-green or gray, mosslike lichen of the genus Usnea, common on rocks and trees. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: usnea (Thesaurus) USNA USNG Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language