| archiannelid | (n) small primitive marine worm lacking external segmentation and resembling polychaete larvae |
| archiannelida | (n) a class of Annelida, Syn. class Archiannelida |
| Archiannelida | ‖n. pl. [ NL.; pref. archi- + annelida. ] (Zool.) A group of Annelida remarkable for having no external segments or distinct ventral nerve ganglions. [ 1913 Webster ] |