From Proto-Germanic *bermô (“yeast, leaven”), from Proto-Indo-European *bher- (“to boil up”), from Proto-Indo-European *bʰrewe- (“to boil, bubble, burn”). Akin to West Frisian berme "barm", Middle Dutch berm, barm (“barm”); dialectal and Low German Bärm, Bärme, from Middle Low German barm, berm; Swedish bärme; Old English brēowan (“to brew”), Old English bēor (“beer”). Cognate to Albanian burmë (“fully ripe”). More at brew, beer.
- English barm