/ Dictionary / Index O opal: Meaning and Definition of Find definitions for: o•pal Pronunciation: (ō'pul), [key] — n. a mineral, an amorphous form of silica, SiO with some water of hydration, found in many varieties and colors, including a form that is milky white. an iridescent variety of this that is used as a gem. a gem of this. O•pal Pronunciation: (ō'pul), [key] — n. a female given name. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: opal (Thesaurus) opah opalesce Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language