Source : Webster's Revised Unabridged Dictionary (1913)

Beast \Beast\, n. [OE. best, beste, OF. beste, F. b[^e]te, fr.
   L. bestia.]
   1. Any living creature; an animal; -- including man, insects,
      etc. [Obs.] --Chaucer.

   2. Any four-footed animal, that may be used for labor, food,
      or sport; as, a beast of burden.

            A righteous man regardeth the life of his beast.
                                                  --Prov. xii.
                                                  10.

   3. As opposed to {man}: Any irrational animal.

   4. Fig.: A coarse, brutal, filthy, or degraded fellow.

   5. A game at cards similar to loo. [Obs.] --Wright.

   6. A penalty at beast, omber, etc. Hence: To be beasted, to
      be beaten at beast, omber, etc.

   {Beast royal}, the lion. [Obs.] --Chaucer.

   Syn: {Beast}, {Brute}.

   Usage: When we use these words in a figurative sense, as
          applicable to human beings, we think of beasts as mere
          animals governed by animal appetite; and of brutes as
          being destitute of reason or moral feeling, and
          governed by unrestrained passion. Hence we speak of
          beastly appetites; beastly indulgences, etc.; and of
          brutal manners; brutal inhumanity; brutal ferocity.
          So, also, we say of a drunkard, that he first made
          himself a beast, and then treated his family like a
          brute.

Source : WordNet®

beast
     n 1: a living organism characterized by voluntary movement [syn:
          {animal}, {animate being}, {brute}, {creature}, {fauna}]
     2: a cruelly rapacious person [syn: {wolf}, {savage}, {brute},
        {wildcat}]