Oat

noun

1. Widely cultivated cereal grass, typically Avena sativa.

   "The main forms of oat are meal and bran."

2. Any of the numerous species, varieties, or cultivars of any of several similar grain plants in genus Avena.

   "The wild red oat is thought to be the ancestor of modern food oats."

3. (usually as plural) The seeds of the oat, a grain, harvested as a food crop.
4. A simple musical pipe made of oat-straw.