processional n.

late Old English, "set of persons walking or riding formally or with ceremonious solemnity; a religious procession; the triumphal entry of Jesus into Jerusalem," from Old French procession "procession" (religious or secular), 11c., and directly from Late Latin processionem (nominative processio) "religious procession," in classical Latin "a marching onward, a going forward, advance," noun of action from past-participle stem of procedere (see proceed). Meaning "act of issuing forth" from anything is late 14c. Related: Processionary.

suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).