Source : Webster's Revised Unabridged Dictionary (1913)

Mixer \Mix"er\, n.
   One who, or that which, mixes.

Mixer \Mix"er\, n.
   A person who has social intercourse with others of many
   sorts; a person viewed as to his casual sociability; --
   commonly used with some characterizing adjective; as, a good
   mixer; a bad mixer. [Colloq. or Slang, U. S.]

Source : WordNet®

mixer
     n 1: a party of people assembled to promote sociability and
          communal activity [syn: {sociable}, {social}]
     2: club soda or fruit juice used to mix with alcohol
     3: electronic equipment that mixes two or more input signals to
        give a single output signal
     4: a kitchen utensil that is used for mixing foods