/ Dictionary / Index U unicostate: Meaning and Definition of Find definitions for: u•ni•cos•tate Pronunciation: (y"ni-kos'tāt, -kô'stāt), [key] — adj. having only one costa, rib, or ridge. (of a leaf&hasp;) having only one primary or prominent rib, the midrib. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. unicorn plant unicuspid Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language