The Collaborative International Dictionary of English v.0.48:

Ousel \Ou"sel\ ([oo^]"z'l), n. [OE. osel, AS. [=o]sle; akin to
   G. amsel, OHG. amsala, and perh. to L. merula blackbird. Cf.
   Merle, Amsel.] (Zool.)
   One of several species of European thrushes, especially the
   blackbird (Merula merula, or Turdus merula), and the
   mountain or ring ousel (Turdus torquatus). [Written also
   ouzel.]
   [1913 Webster]

   Rock ousel (Zool.), the ring ousel.

   Water ousel (Zool.), the European dipper (Cinclus
      aquaticus), and the American dipper (Cinclus
      Mexicanus).
      [1913 Webster]