Quick definitions from WordNet (invocation)
▸ noun: the act of appealing for help
▸ noun: an incantation used in conjuring or summoning a devil
▸ noun: a prayer asking God's help as part of a religious service
▸ noun: calling up a spirit or devil
▸ Also see invocation
▸ noun: the act of appealing for help
▸ noun: an incantation used in conjuring or summoning a devil
▸ noun: a prayer asking God's help as part of a religious service
▸ noun: calling up a spirit or devil
▸ Also see invocation