The Collaborative International Dictionary of English v.0.48:

Papilio \Pa*pil"i*o\, peop. n. [L., a butterfly.] (Zool.)
   A genus of butterflies.
   [1913 Webster]

   Note: Formerly it included numerous species which are now
         placed in other genera. By many writers it is now
         restricted to the swallow-tailed butterflies, like
         Papilio polyxenes, syn. Papilio asterias, and
         related species.
         [1913 Webster]