From The Collaborative International Dictionary of English v.0.48 [gcide]:
Oat \Oat\ ([=o]t), n.; pl. Oats ([=o]ts). [OE. ote, ate, AS.
[=a]ta, akin to Fries. oat. Of uncertain origin.]
1. (Bot.) A well-known cereal grass (Avena sativa), and its
edible grain, used as food and fodder; -- commonly used in
the plural and in a collective sense.
[1913 Webster]
2. A musical pipe made of oat straw. [Obs.] --Milton.
[1913 Webster]
Animated oats or Animal oats (Bot.), A grass ({Avena
sterilis}) much like oats, but with a long spirally
twisted awn which coils and uncoils with changes of
moisture, and thus gives the grains an apparently
automatic motion.
Oat fowl (Zool.), the snow bunting; -- so called from its
feeding on oats. [Prov. Eng.]
Oat grass (Bot.), the name of several grasses more or less
resembling oats, as Danthonia spicata, {Danthonia
sericea}, and Arrhenatherum avenaceum, all common in
parts of the United States.
To feel one's oats,
(a) to be conceited or self-important. [Slang]
(b) to feel lively and energetic.
To sow one's wild oats, to indulge in youthful dissipation.
--Thackeray.
Wild oats (Bot.), a grass (Avena fatua) much resembling
oats, and by some persons supposed to be the original of
cultivated oats.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
wild oats
n 1: any of various plants of the genus Uvularia having
yellowish drooping bell-shaped flowers [syn: bellwort,
merry bells, wild oats]