/ Dictionary / Index O ossein: Meaning and Definition of Find definitions for: os•se•in Pronunciation: (os'ē-in), [key] — n. Biochem. the collagen of bone, remaining after the mineral matter has been removed by treatment with dilute acid. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ossa osselet Related Content Daily Word Quiz: abstain Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language