Originally: †belonging to a former group Abranchiata or Abranchiatae of annelids (obsolete). In later use: (more generally) having no gills; not bearing gills.
Mid 19th century; earliest use found in Henry McMurtrie (1793–1865). From a- + ancient Greek βράγχια gills + -ate, after scientific Latin Abranchiata, Abranchiatae, group names, which are in turn after French Abranches, plural noun. Compare French abranche (adjective) belonging to a former group of annelids.