ace in the hole
01
a secret resource, skill, etc. that a person can use to their advantage when the need arises
Dialect
American
American
Idiom
Informal
예시들
She's keeping all the details of their unscrupulous business practices as an ace in the hole should they ever try to fire her.
She kept her best idea as her ace in the hole, ready to present it when the timing was perfect.
