Ace up your sleeve

Meaning

A secret advantage saved for a decisive moment.

Usage

Used when someone has reserves they plan to reveal later.

Origin & History

Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.

Gambling metaphor where a player hides a strong card.

19th-century gambling slang that entered everyday speech.