/ Dictionary / Index S semilunar bone: Meaning and Definition of Find definitions for: sem'ilu'nar bone' Pronunciation: [key] lunate (def. 2). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. semilunar semilunar valve Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language