The Collaborative International Dictionary of English v.0.48:

Goosander \Goos"an`der\, n. [OE. gossander, a tautological word
   formed fr. goose + gander. Cf. Merganser.] (Zool.)
   A species of merganser (M. merganser) of Northern Europe
   and America; -- called also merganser, dundiver,
   sawbill, sawneb, shelduck, and sheldrake. See
   Merganser.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sawbill \Saw"bill`\, n.
   The merganser. [Prov. Eng.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Merganser \Mer*gan"ser\, n. [Sp. merg['a]nsar, fr. mergo a diver
   (L. mergus, fr. mergere to dip, dive) + ['a]nsar goose, L.
   anser.] (Zool.)
   Any bird of the genus Mergus (Merganser), and allied
   genera of the subfamily Merginae. They are allied to the
   ducks, but have a sharply serrated bill, eat fish, and dive
   for food. Also called fish duck.
   [1913 Webster +PJC]

   Note: The red-breasted merganser (Merganser serrator)
         inhabits both hemispheres. It is called also sawbill,
         harle, and sheldrake. The American merganser
         (Merganser Americanus.) and the hooded merganser
         (Lophodytes cucullatus) are well-known species.

   White merganser, the smew or white nun.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sawbill
    n 1: large crested fish-eating diving duck having a slender
         hooked bill with serrated edges [syn: merganser, fish
         duck, sawbill, sheldrake]