/ Dictionary / Index R residuum: Meaning and Definition of Find definitions for: re•sid•u•um Pronunciation: (ri-zij'-um), [key] — pl. -sid•u•a the residue, remainder, or rest of something. a quantity or body of matter remaining after evaporation, combustion, distillation, etc. any residual product. the residue of an estate. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: residuum (Thesaurus) residue re-sign Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language