mouse Look up mouse at Dictionary.com
O.E. mus "small rodent," also "muscle," from P.Gmc. *mus (cf. O.N., O.Fris., M.Du. mus, Ger. Maus "mouse"), from PIE *muHs- (cf. Skt. mus "mouse, rat," O.Pers. mush "mouse," O.C.S. mysu, L. mus, Lith. muse "mouse," Gk. mys "mouse, muscle"). Plural form mice (O.E. mys) shows effects of i-mutation. Meaning "black eye" (or other discolored lump) is from 1842. Computer sense is from 1965, though applied to other things resembling a mouse in shape since 1750, mainly nautical. Mousetrap is from c.1475 (O.E. had musfealle).