Relativistic

Part of speech: adjective

Pronunciation: /ˈɹɛl.ə.təˌvɪst.ɪk/

Definitions

1. Pertaining to a theoretical framework whereby physical attributes and perceptions are influenced by the relative velocities of observers moving close to light speed
2. Concerning a theoretical perspective that emphasizes how physical phenomena and measurements are affected by the relative motion of observers traveling at significant fractions of light speed
3. Connected to concepts in physics where observations change based on the speed of the observer relative to the speed of light

Etymology: "Relativistic" is built from "relative" and the suffix "-istic," with the "relativist" route also possible as a source. The "-istic" ending marks something as characteristic of a doctrine or theory, which is why the word can describe a theory itself rather than merely a thing that is relative. Its meaning comes straight from Einstein's physics, where relativity describes how measured time, length and mass depend on the relative speed of the observer, especially at speeds approaching that of light. The surprise is how ordinary the parts are. "Relative" traces back through Old French to Latin "relativus," meaning referring back to something, and the English adjective long predates physics, meaning comparative or dependent on something else. The physics sense simply took that older idea of dependence on a point of reference and applied it to motion. A word about comparison therefore became a word about the measurable reshaping of time and space.