/ Dictionary / Index R relativistic: Meaning and Definition of Find definitions for: rel•a•tiv•is•tic Pronunciation: (rel"u-tu-vis'tik), [key] — adj. of or pertaining to relativity or relativism. radiation from relativistic electrons. subject to the special or the general theory of relativity. (of a velocity) having a magnitude that is a significant fraction of the speed of light. (of a particle) having a relativistic velocity:radiation from relativistic electrons. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: relativistic (Thesaurus) relativist relativistic mass Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language