n. A cereal plant, Avena sativa, or its seed: commonly used in the plural in a collective sense.n. Any species of Avena. The wild oat of Europe, A. fatua, is a weed of cultivation in many places; in California, where it abounds, it is extensively utilized as hay. The animal, fly, or hygrometric oat, A. sterilis, native in Barbary, has two long, strong, much-bent awns, which twist and untwist with changes of moisture, and so become a means of locomotion. Various species are more or less available for pasture.n. A musical pipe of oat-straw; a shepherd's pipe; hence, pastoral song. See oaten pipe, under oaten.n. Bromus secalinus.n. Pharus latifolius.To feed with oats; feed oats to.