a. [ Cf. LL. processionarius, F. processionnaire. ] Pertaining to a procession; consisting in processions; as, processionary service. [ 1913 Webster ]

Processionary moth (Zool.), any moth of the genus Cnethocampa, especially Cnethocampa processionea of Europe, whose larvæ make large webs on oak trees, and go out to feed in regular order. They are covered with stinging hairs. [ 1913 Webster ]