/ Dictionary / Index O oil-harden: Meaning and Definition of Find definitions for: oil-hard•en Pronunciation: (oil'här"dn), [key] — v.t. Metall. to quench (steel) in a bath of oil. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. oil gland oil-immersion objective Related Content Daily Word Quiz: diligent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language