Relativistic /(?)/

Rel·a·tiv·ist·ic

Relativistic

a.
  1. of, pertaining to, or in conformity with the theory of relativity; as, the relativistic increase of mass with velocity.
  2. moving at a speed sufficiently high that the changes of mass or time dilation predicted by the theory of relativity may be observed; moving at a significant fraction of the speed of light; as, relativistic electrons.