/ Dictionary / Index D decaf: Meaning and Definition of Find definitions for: de•caf Pronunciation: (dē'kaf"), [key] — Informal. Informal. —n. decaffeinated coffee or tea. —adj. decaffeinated. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: decaf (Thesaurus) Decadron decaffeinate Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language