The DICT Development Group

  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.)
     Mergus+({Merganser">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]