malt. n. 1. Grain, usually barley, that has been allowed to sprout, used chiefly in brewing and distilling. 2. An alcoholic beverage, such as beer or ale, brewed from malt.3.alt. n. 1. Grain, usually barley, that has been allowed to sprout, used chiefly in brewing and distilling. 2. An alcoholic beverage, such as beer or ale, brewed from malt. 3.