The Collaborative International Dictionary of English v.0.48:

Siphonostomata \Si`pho*no*stom"a*ta\, n. pl. [NL. See Siphon,
   and Stoma.] (Zool.)
   (a) A tribe of parasitic copepod Crustacea including a large
       number of species that are parasites of fishes, as the
       lerneans. They have a mouth adapted to suck blood.
   (b) An artificial division of gastropods including those that
       have siphonostomatous shells.
       [1913 Webster]

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]