[Cnidaria] 1) Colloquial name for a hydroid of the former group Athecata (here incorporated within the Anthoathecatae), all of which lack a proper hydrotheca
2) Implying lack of any kind of theca, i.e., having no hydrotheca, gonotheca, or nematotheca; these kinds of thecae are usually absent (or present) as a group, but athecate usually refers to absence of the hydrotheca.
Thecate implies such thecae, especially hydrothecae, are present, and corresponds to the hydroid stage of the group here called Leptothecata. The terms athecate and thecate are used implicitly for the hydroid stages, anthoathecate and leptothecate embrace hydroid and medusa stages equally.