Definition of barm

• n. - Foam rising upon beer, or other malt liquors, when fermenting, and used as leaven in making bread and in brewing; yeast.
• n. - The lap or bosom.
• n. - Foam rising upon beer, or other malt liquors, when fermenting, and used as leaven in making bread and in brewing; yeast.
• n. - The lap or bosom.