Source : Webster's Revised Unabridged Dictionary (1913)

Massasauga \Mas`sa*sau"ga\, n. (Zo["o]l.)
   The black rattlesnake ({Crotalus, or Caudisona, tergemina}),
   found in the Mississippi Valley.

Source : WordNet®

massasauga
     n 1: small pygmy rattlesnake [syn: {ground rattler}, {Sistrurus
          miliaris}]
     2: pygmy rattlesnake found in moist areas from the Great Lakes
        to Mexico; feeds on mice and small amphibians [syn: {massasauga
        rattler}, {Sistrurus catenatus}]