The story
- Classical Latin · derived fromgermāna soror
- Anglo-Norman and Middle French · derived fromsuer germaine
- Middle English · inherited fromsister germain
- English todaysister-german
From Middle English sister germain, equivalent to sister + german, after Anglo-Norman and Middle French suer germaine and its etymon Classical Latin germāna soror.
Etymology from Wiktionary, CC BY-SA 4.0.