to petition (e.g. a deity) for help or support
to appeal to (an arbitrator or other authority) for help, a judgment, confirmation of an opinion, etc
to call forth (e.g. a spirit) by uttering a spell or magical formula
to make an earnest request for (something)
We invoked their forgiveness
to put (something) into effect
They may invoke economic sanctions
invocable adj
invoker noun
[Middle English invoken via French from Latin invocare, from in-2 + vocare to call]