The Collaborative International Dictionary of English v.0.48:

Anadromous \A*nad"ro*mous\, a. [Gr. ? running upward; ? + ? a
   running, ? to run.]
   1. (Zool.) Ascending rivers from the sea, at certain seasons,
      for breeding, as the salmon, shad, etc.
      [1913 Webster]

   2. (Bot.) Tending upwards; -- said of terns in which the
      lowest secondary segments are on the upper side of the
      branch of the central stem. --D. C. Eaton.
      [1913 Webster] Anemia

WordNet (r) 3.0 (2006):

anadromous
    adj 1: migrating from the sea to fresh water to spawn [ant:
           catadromous, diadromous]