Wordnet 3.0
NOUN (1)
1. 
 found in Pacific coastal waters and streams from lower California to Alaska; 
[syn: rainbow trout, Salmo gairdneri]
The Collaborative International Dictionary of English v.0.48:
Steelhead \Steel"head`\ (-h[e^]d`), n.
   1. (Zool.) A North Pacific salmon (Salmo Gairdneri) found
      from Northern California to Siberia; -- called also
      hardhead, and preestl.
      [1913 Webster]
   2. (Zool.) The ruddy duck.
      [1913 Webster]
WordNet (r) 3.0 (2006):
Salmo gairdneri
    n 1: found in Pacific coastal waters and streams from lower
         California to Alaska [syn: rainbow trout, Salmo
         gairdneri]