The Collaborative International Dictionary of English v.0.48:

Seal \Seal\ (s[=e]l), n. [OE. sele, AS. seolh; akin to OHG.
   selah, Dan. sael, Sw. sj[aum]l, Icel. selr.] (Zool.)
   Any aquatic carnivorous mammal of the families Phocidae and
   Otariidae.
   [1913 Webster]

   Note: Seals inhabit seacoasts, and are found principally in
         the higher latitudes of both hemispheres. There are
         numerous species, bearing such popular names as sea
         lion, sea leopard, sea bear, or ursine seal,
         fur seal, and sea elephant. The bearded seal
         (Erignathus barbatus), the hooded seal (Cystophora
         cristata), and the ringed seal (Phoca foetida), are
         northern species. See also Eared seal, Harp seal,
         Monk seal, and Fur seal, under Eared, Harp,
         Monk, and Fur. Seals are much hunted for their
         skins and fur, and also for their oil, which in some
         species is very abundant.
         [1913 Webster]

   Harbor seal (Zool.), the common seal (Phoca vitulina). It
      inhabits both the North Atlantic and the North Pacific
      Ocean, and often ascends rivers; -- called also marbled
      seal, native seal, river seal, bay seal, land
      seal, sea calf, sea cat, sea dog, dotard,
      ranger, selchie, tangfish.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hooded \Hood"ed\, a.
   1. Covered with a hood.
      [1913 Webster]

   2. Furnished with a hood or something like a hood.
      [1913 Webster]

   3. Hood-shaped; esp. (Bot.), rolled up like a cornet of
      paper; cuculate, as the spethe of the Indian turnip.
      [1913 Webster]

   4. (Zool.)
      (a) Having the head conspicuously different in color from
          the rest of the plumage; -- said of birds.
      (b) Having a hoodlike crest or prominence on the head or
          neck; as, the hooded seal; a hooded snake.
          [1913 Webster]

   Hooded crow, a European crow (Corvus cornix); -- called
      also hoody, dun crow, and royston crow.

   Hooded gull, the European black-headed pewit or gull.

   Hooded merganser. See Merganser.

   Hooded seal, a large North Atlantic seal (Cystophora
      cristata). The male has a large, inflatible, hoodlike sac
      upon the head. Called also hoodcap.

   Hooded sheldrake, the hooded merganser. See Merganser.

   Hooded snake. See Cobra de capello, Asp, Haje, etc.


   Hooded warbler, a small American warbler (Sylvania
      mitrata).
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

bladdernose \blad"der*nose\ n.
   a medium-sized blackish-gray seal (Cystophora cristata)
   with a large inflatable sac on the head; of Arctic-Atlantic
   waters.

   Syn: hooded seal.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Cystophora cristata
    n 1: medium-sized blackish-grey seal with large inflatable sac
         on the head; of Arctic and northern Atlantic waters [syn:
         hooded seal, bladdernose, Cystophora cristata]