/ Dictionary / Index O opacity: Meaning and Definition of Find definitions for: o•pac•i•ty Pronunciation: (ō-pas'i-tē), [key] — pl. -ties. the state or quality of being opaque. something opaque. the degree to which a substance is opaque; capacity for being opaque. the proportion of the light that is absorbed by the emulsion on any given area of a film or plate. obscurity of meaning. mental dullness. an opaque spot or area in normally clear or transparent tissue, as a cataract of the eye. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: opacity (Thesaurus) opacify opacus Related Content Daily Word Quiz: profiterole Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language