Source : Webster's Revised Unabridged Dictionary (1913)

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; -- commonly used in the plural and in a
      collective sense.

   2. A musical pipe made of oat straw. [Obs.] --Milton.

   {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} (Zo["o]l.), 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}, {D. sericea}, and
      {Arrhenatherum avenaceum}, all common in parts of the
      United States.

   {To feel one's oats}, to be conceited ro self-important.
      [Slang]

   {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.

Avena \A*ve"na\, n. [L.] (Bot.)
   A genus of grasses, including the common oat ({Avena
   sativa}); the oat grasses.

Source : WordNet®

Avena sativa
     n : widely cultivated in temperate regions for its edible grains
         [syn: {cereal oat}]