Mergus albellus

from WordNet (r) 3.0 (2006)

Mergus albellus
    n 1: smallest merganser and most expert diver; found in northern
         Eurasia [syn: {smew}, {Mergus albellus}]

from The Collaborative International Dictionary of English v.0.48

Smew \Smew\, n. [Perhaps for ice-mew.] (Zool.)
   (a) small European merganser ({Mergus albellus}) which has a
       white crest; -- called also {smee}, {smee duck}, {white
       merganser}, and {white nun}.
   (b) The hooded merganser. [Local, U.S.]
       [1913 Webster]