light speed lights-out • light-spirited · · · Info · Definitions · Synonyms · Characters · · light speed · · Text Common · · Latin · · Scripts 11 · · Length 2 · · Syllables Definitions · · · (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. Synonyms: speed of light, light speed, c. · · Noun Definition 1 Synonyms · · · speed of light · · Synonym 1 c · · Synonym 2 Characters · · space U+0020 d latin small letter d U+0064 e latin small letter e U+0065 g latin small letter g U+0067 h latin small letter h U+0068 i latin small letter i U+0069 l latin small letter l U+006C p latin small letter p U+0070 s latin small letter s U+0073 t latin small letter t U+0074