processional (n.) Look up processional at Dictionary.com
"book of hymns for use in processions," mid-15c., from Medieval Latin processionale, from noun use of neuter of processionalis "pertaining to a procession," from Late Latin processio (see procession).
processional (adj.) Look up processional at Dictionary.com
"pertaining to a procession or processions," 1610s, from procession (n.) + -al (1).