Source : Webster's Revised Unabridged Dictionary (1913)

Nepa \Ne"pa\, n. [L. nepa scorpion.] (Zo["o]l.)
   A genus of aquatic hemipterus insects. The species feed upon
   other insects and are noted for their voracity; -- called
   also {scorpion bug} and {water scorpion}.

Source : WordNet®

Nepa
     n : type genus of the Nepidae: typical elongate-oval water
         scorpions [syn: {genus Nepa}]