/ Dictionary / Index U umbonate: Meaning and Definition of Find definitions for: um•bo•nate Pronunciation: (um'bu-nit, -nāt"), [key] — adj. having an umbo or projecting boss. shaped like an umbo; having a rounded convex form: an umbonate fungus. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. umbonal umbra Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language