Definition of barm
: yeast formed on fermenting malt liquors
Origin and Etymology of barm
Middle English berme, from Old English beorma; akin to Middle Low German berm yeast, Latin fermentum yeast, fervēre to boil, Old Irish berbaid he boils
First Known Use: before 12th century
Seen and Heard
What made you want to look up barm? Please tell us where you read or heard it (including the quote, if possible).