Where does “muis” come from?

muis (Middle English) comes from Old English mȳs, from Proto-Germanic mūsiz, from Proto-Germanic mūs, from Proto-Indo-European múh₂s — mouse.

Ancestry of “muis”, step by step

StepLanguageWordMeaning
1Old Englishmȳsmice
2Proto-Germanicmūsizmice
3Proto-Germanicmūsmouse
4Proto-Indo-Europeanmúh₂smouse
Every word from Proto-Indo-European múh₂s →Every word from Proto-Germanic mūs →Every word from Proto-Germanic mūsiz →