/ Dictionary / Index O oxacillin: Meaning and Definition of Find definitions for: ox•a•cil•lin Pronunciation: (ok"su-sil'in), [key] — n. Pharm. a semisynthetic penicillin, CHNOS, used in the treatment of serious staphylococcal infections. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: oxacillin (Thesaurus) ox oxalate Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language