The Collaborative International Dictionary of English v.0.48:

Cantharides \Can*thar"i*des\ (k[a^]n*th[a^]r"[i^]*d[=e]z), n.
   pl.
   See Cantharis.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cantharis \Can"tha*ris\ (k[a^]n"th[.a]*r[i^]s), n.; pl.
   Cantharides (k[a^]n*th[a^]r"[i^]*d[=e]z). [L., a kind of
   beetle, esp. the Spanish fly, Gr. kanqari`s.] (Zool.)
   A beetle (Lytta vesicatoria, syn. Cantharis vesicatoria),
   having an elongated cylindrical body of a brilliant green
   color, and a nauseous odor; the blister fly or blister
   beetle, of the apothecary; -- also called Spanish fly. Many
   other species of Lytta, used for the same purpose, take the
   same name. See Blister beetle, under Blister. The plural
   form in usually applied to the dried insects used in
   medicine.
   [1913 Webster]