the Devil
noun (1)Definition of the Devil
(Entry 1 of 2)
: the most powerful spirit of evil in Christianity, Judaism, and Islam who is often represented as the ruler of hell
the devil
noun (2)Definition of the devil (Entry 2 of 2)
informal
1
—used to make a statement or question more forceful What the devil are you talking about?Where the devil have you been?
2
: something that is very difficult or that causes a lot of trouble
The shoes look great, but they're the devil to walk in.