mouse: [OE] Mouse is an ancient word, with relatives today in all the Germanic and Slavic languages. Its Indo-European ancestor was *mūs-, which produced Greek mūs, Latin mūs (something of a dead end: the modern Romance languages have abandoned it), Sanskrit mūs (source, via a very circuitous route, of English musk), and prehistoric Germanic *mūs-.
This has evolved into German maus, Dutch muis, Swedish and Danish mus, and English mouse. And the Slavic branch of the ‘mouse’-family includes Russian mysh’, Polish mysz, and Serbo- Croat mish. English relatives of mouse include muscle and mussel (ultimately the same word) and marmot [17], which goes back to a Vulgar Latin accusative form *mūrem montis ‘mouse of the mountain’. => marmot, muscle, musk, mussel
mouse (n.)
Old English mus "small rodent," also "muscle of the arm," from Proto-Germanic *mus (cognates: Old Norse, Old Frisian, Middle Dutch, Danish, Swedish mus, Dutch muis, German Maus "mouse"), from PIE *mus- (cognates: Sanskrit mus "mouse, rat," Old Persian mush "mouse," Old Church Slavonic mysu, Latin mus, Lithuanian muse "mouse," Greek mys "mouse, muscle").
Plural form mice (Old English mys) shows effects of i-mutation. Contrasted with man (n.) from 1620s. 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.
