1. the foam or scum formed on the top of liquor when fermenting
2. yeast formed on such liquor and used in baking bread

Examples

• The baker skimmed the barm from the fermenting ale.
• She used fresh barm to make the bread rise.
• The barm on top of the beer indicated active fermentation.
• Traditional bakers preferred barm over commercial yeast.
• The thick barm was carefully collected for the next batch of bread.
• Without proper barm, the loaves would remain flat and dense.