Definition of an ace up one's sleeve or in the hole in English:
A plan or piece of information kept secret until it becomes necessary to use it.
- Also tomorrow, we have another ace up our sleeve.
- No sane person wants to get into a ‘knife fight,’ but it's comforting to have an ace up your sleeve if trouble finds you.
- That's why you may need an ace up your sleeve for these lavish projects: the European-style kitchen system.