relativistic

adjective

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.

adjective

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

1. Either of two theories in physics developed by Albert Einstein, General Relativity or Special Relativity. See Notes at Einstein gravity space-time.