The Collaborative International Dictionary
Processionary moth
Processionary \Pro*ces"sion*a*ry\, a. [Cf. LL. processionarius, F. processionnaire.] Pertaining to a procession; consisting in processions; as, processionary service.
Processionary moth (Zo["o]l.), any moth of the genus Cnethocampa, especially Cnethocampa processionea of Europe, whose larv[ae] make large webs on oak trees, and go out to feed in regular order. They are covered with stinging hairs.