1. Plural of barm; froth or foam that forms on fermenting beer or other liquids during brewing.
Usage: chiefly British; technical/brewing context
2. Plural of barm; the yeast or leavening agent used in baking, especially in traditional British baking.
Usage: chiefly British; archaic or regional

Examples

• The brewer skimmed the barms from the top of the fermenting vat.
• Traditional barms cakes are a specialty in Lancashire.
• The barms rose to the surface as the beer fermented.
• She used barms from the local brewery to leaven her bread.
• The thick layer of barms indicated active fermentation.