Source : Webster's Revised Unabridged Dictionary (1913)

Geezer \Gee"zer\, n. [Dial. corrupt. of {Guiser} a mummer.]
   A queer old fellow; an old chap; an old woman. [Contemptuous,
   Slang or Dial.]

Source : WordNet®

geezer
     n : a man who is (usually) old and/or eccentric [syn: {bloke}]