To call on for aid or protection; to invite earnestly or solemnly; to summon; to address in prayer; to solicit or demand by invocation; to implore; as, to invoke the Supreme Being, or to invoke His and blessing
{f} requests help or protection (from a deity); summon a spirit through witchcraft; request, make an appeal; pray; activate a command, cause a certain action (Computers)
(v ) to call a subroutine by a CALL statement or by a defined assignment statement To call a function by a reference to it by name or operator during the evaluation of an expression
To ritually "call in" a spirit, entity or energy higher than that of the human form This is most commonly recognised through the ritual of Drawing Down the Moon The purpose can vary from wishing to contact a loved one who has passed over to drawing upon the wisdom and knowledge of the chosen Deity However, I would strongly advise against using this practise until you are entirely confident of being stable enough to handle such strong energies within your own body