Source : Webster's Revised Unabridged Dictionary (1913)

Abranchiata \A*bran`chi*a"ta\, n. pl. [NL., from Gr. 'a priv. +
   ?, pl., the gills of fishes.] (Zo["o]l.)
   A group of annelids, so called because the species composing
   it have no special organs of respiration.