n. 1 a a cereal plant, Avena sativa, cultivated in cool climates. b (in pl.) the grain yielded by this, used as food. 2 any other cereal of the genus Avena, esp. the wild oat, A. fatua. 3 poet. the oat-stem used as a musical pipe by shepherds etc., usu. in pastoral or bucolic poetry. 4 (in pl.) sl. sexual gratification. feel one's oats colloq. 1 be lively. 2 US feel self-important. oat-grass any of various grasses, esp. of the genus Arrhenatherum. off one's oats colloq. not hungry. sow one's oats (or wild oats) indulge in youthful excess or promiscuity. oaten adj.
[ OE ate, pl. atan, of unkn. orig. ]