What's the adjective for processible? Here's the word you're looking for.
Included below are past participle and present participle forms for the
verbs process and procession which may be used as adjectives within certain contexts.
“After attending a festive celebration at one suburban parish, he sent a note to the pastor, telling him to place a corpus on the processional cross and to reconfigure the tilt of the altar to conform to church rubrics.”