mass-energy equivalence mass-energy equation • massenet · · · Info · Definitions · Characters · · mass-energy equivalence · · Text Common · · Latin · · Scripts 23 · · Length 9 · · Syllables Definitions · · · (noun) (physics) the principle that a measured quantity of mass is equivalent (according to relativity theory) to a measured quantity of energy. Synonyms: mass-energy equivalence. · · Noun Definition 1 Characters · · space U+0020 - hyphen-minus U+002D a latin small letter a U+0061 c latin small letter c U+0063 e latin small letter e U+0065 g latin small letter g U+0067 i latin small letter i U+0069 l latin small letter l U+006C m latin small letter m U+006D n latin small letter n U+006E q latin small letter q U+0071 r latin small letter r U+0072 s latin small letter s U+0073 u latin small letter u U+0075 v latin small letter v U+0076 y latin small letter y U+0079