Gay-lussac gay-looking • gay-motleyed · · · Info · Definitions · Characters · · Gay-lussac · · Text Common · · Latin · · Scripts 10 · · Length Definitions · · · (noun) French chemist and physicist who first isolated boron and who formulated the law describing the behavior of gases under constant pressure (1778-1850). Synonyms: Gay-Lussac, Joseph Louis Gay-Lussac. · · Noun Definition 1 Characters · · - hyphen-minus U+002D G latin capital letter g U+0047 a latin small letter a U+0061 c latin small letter c U+0063 l latin small letter l U+006C s latin small letter s U+0073 u latin small letter u U+0075 y latin small letter y U+0079