noun Ga·ius [gey-uh s] /ˈgeɪ əs/ (or Ca·ius) [key-uh s] /ˈkeɪ əs/ Mu·ci·us [myoo-shee-uh s, -shuh s] /ˈmyu ʃi əs, -ʃəs/, fl. 6th century b.c., Roman hero.