1. of or relating to relativity or relativism.
  2. Physics.
    1. subject to the special or the general theory of relativity.
    2. (of a velocity) having a magnitude that is a significant fraction of the speed of light.
    3. (of a particle) having a relativistic velocity: radiation from relativistic electrons.

Origin of relativistic

First recorded in 1885–90; relativist + -ic
Related formsrel·a·tiv·is·ti·cal·ly, adverbul·tra·rel·a·tiv·is·tic, adjectiveun·rel·a·tiv·is·tic, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for relativistically


  1. physics having or involving a speed close to that of light so that the behaviour is described by the theory of relativity rather than by Newtonian mechanicsa relativistic electron; a relativistic velocity
  2. physics of, concerned with, or involving relativity
  3. of or relating to relativism
Derived Formsrelativistically, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012