Constant
Constant noun - A quantity that does not vary.
Light speed and constant are semantically related. In some cases you can replace phrase "Light speed" with "Constant", this terms are similar.
Light speed
Light speed noun - The speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second.
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Synonyms for Light speed
Constant and light speed are semantically related. You can use "Constant" instead a noun phrase "Light speed".
Both terms in one sentence
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It was Hendrik Lorentz that first came up with the idea that light speed is constant, and it was Henri Poincare who originally came up with the equation E = mc2, only he wrote it as "m = E/c2".
Source: Useful Notes / Albert Einstein - For the Flash, there is an implant that gives him constant uncontrollable seizures at light speed.
Source: Betrayal Insurance
Cite this Source
Light speed and Constant. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/constant/light_speed
Constant & Light speed. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/constant/light_speed>.
Light speed or Constant. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/constant/light_speed.
Google Ngram Viewer shows how "constant" and "light speed" have occurred on timeline