What does "barley" mean?

Barley: A valuable grain, of the family of grasses, genus Hordeum, used for food, and for making malt, from which are prepared beer, ale, and whisky. Barley bird (Zoöl.), the siskin. -- Barley sugar, sugar boiled till it is brittle (formerly with a decoction of barley) and candied. -- Barley water, a decoction of barley, used in medicine, as a nutritive and demulcent.