1.noun(authorship) Any resolution to a story that does not pay due regard to the story's internal logic and that is so unlikely that it challenges suspension of disbelief, and presumably allows the author, director, or developer to end the story in the way that he or she desired.
"Oh, now I'm backed into a corner, and can't devise a way out. I could sure use a deus ex machina right about now!"
2.nounA contrived solution to a problem, relying on an agent external to the situation.
"We used a sale of the business at a ridiculously high multiple to make the numbers work, a deus ex machina."
3.nounA machine used to bring actors playing gods onto the stage, either up through a trapdoor or (e.g. by crane) from above.