The Collaborative International Dictionary of English v.0.48:

Parasita \Par`a*si"ta\ (p[a^]r`[.a]*s[imac]"t[.a]), n. pl. [NL.]
   (Zool.)
   (a) An artificial group formerly made for parasitic insects,
       as lice, ticks, mites, etc.
   (b) A division of copepod Crustacea, having a sucking mouth,
       as the lerneans. They are mostly parasites on fishes.
       Called also Siphonostomata.
       [1913 Webster]