The Collaborative International Dictionary of English v.0.48:

Salmon \Salm"on\ (s[a^]m"[u^]n), n.; pl. Salmons (-[u^]nz) or
   (collectively) Salmon. [OE. saumoun, salmon, F. saumon, fr.
   L. salmo, salmonis, perhaps from salire to leap. Cf. Sally,
   v.]
   1. (Zool.) Any one of several species of fishes of the genus
      Salmo and allied genera. The common salmon (Salmo
      salar) of Northern Europe and Eastern North America, and
      the California salmon, or quinnat, are the most important
      species. They are extensively preserved for food. See
      Quinnat.
      [1913 Webster]
      [1913 Webster]

   Note: The salmons ascend rivers and penetrate to their head
         streams to spawn. They are remarkably strong fishes,
         and will even leap over considerable falls which lie in
         the way of their progress. The common salmon has been
         known to grow to the weight of seventy-five pounds;
         more generally it is from fifteen to twenty-five
         pounds. Young salmon are called parr, peal, smolt, and
         grilse. Among the true salmons are:

   Black salmon, or Lake salmon, the namaycush.

   Dog salmon, a salmon of Western North America
      (Oncorhynchus keta).

   Humpbacked salmon, a Pacific-coast salmon (Oncorhynchus
      gorbuscha).

   King salmon, the quinnat.

   Landlocked salmon, a variety of the common salmon (var.
      Sebago), long confined in certain lakes in consequence of
      obstructions that prevented it from returning to the sea.
      This last is called also dwarf salmon.
      [1913 Webster]

   Note: Among fishes of other families which are locally and
         erroneously called salmon are: the pike perch, called
         jack salmon; the spotted, or southern, squeteague;
         the cabrilla, called kelp salmon; young pollock,
         called sea salmon; and the California yellowtail.
         [1913 Webster]

   2. A reddish yellow or orange color, like the flesh of the
      salmon.
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   Salmon berry (Bot.), a large red raspberry growing from
      Alaska to California, the fruit of the Rubus Nutkanus.


   Salmon killer (Zool.), a stickleback (Gasterosteus
      cataphractus) of Western North America and Northern Asia.


   Salmon ladder, Salmon stair. See Fish ladder, under
      Fish.

   Salmon peel, a young salmon.

   Salmon pipe, a certain device for catching salmon. --Crabb.

   Salmon trout. (Zool.)
      (a) The European sea trout (Salmo trutta). It resembles
          the salmon, but is smaller, and has smaller and more
          numerous scales.
      (b) The American namaycush.
      (c) A name that is also applied locally to the adult black
          spotted trout (Salmo purpuratus), and to the steel
          head and other large trout of the Pacific coast.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Salmo salar
    n 1: found in northern coastal Atlantic waters or tributaries;
         adults do not die after spawning [syn: Atlantic salmon,
         Salmo salar]