The Collaborative International Dictionary of English v.0.48:

Acipenser \Ac`i*pen"ser\, prop. n. [L., the name of a fish.]
   (Zool.)
   A genus of ganoid fishes, including the sturgeons, having the
   body armed with bony scales, and the mouth on the under side
   of the head. See Sturgeon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Acipenser
    n 1: type genus of the Acipenseridae: sturgeons [syn:
         Acipenser, genus Acipenser]