Where does “Westmoustier” come from?

Westmoustier (Middle French) comes from Old French Westmostier, from Middle English Westmynster, from Old English Westmynster, from Old English west, from Proto-West Germanic *westr, from Proto-Germanic westrą, from Proto-Germanic westraz, from Proto-Indo-European wek(ʷ)speros.

Ancestry of “Westmoustier”, step by step

StepLanguageWordMeaning
1Old FrenchWestmostier
2Middle EnglishWestmynster
3Old EnglishWestmynster
4Old Englishwestwest
5Proto-West Germanic*westrwestern, westernly
6Proto-Germanicwestrąwest; west, westward
7Proto-Germanicwestrazwest, western
8Proto-Indo-Europeanwek(ʷ)sperosevening
9Proto-Indo-Europeanwe-
Every word from Proto-Indo-European we-Every word from Proto-Indo-European wek(ʷ)sperosEvery word from Proto-Germanic westraz