The Collaborative International Dictionary of English v.0.48:

Hamster \Ham"ster\ (-st[~e]r), n. [G. hamster.] (Zool.)
   A small European rodent (Cricetus frumentarius). It is
   remarkable for having a pouch on each side of the jaw, under
   the skin, and for its migrations. Hamsters are commonly kept
   as a pets.
   [1913 Webster +PJC]