oat(redirected from oat hay)
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1. an erect annual grass, Avena sativa, grown in temperate regions for its edible seed
2. the seeds or fruits of this grass
3. any of various other grasses of the genus Avena, such as the wild oat
4. Poetic Music a flute made from an oat straw
Any plant of the genus Avena in the family Graminae, cultivated as an agricultural crop for its seed, a cereal grain, and for straw.