Cool as a cucumber

Meaning

Calm and collected under stress.

Usage

Compliments someone who stays calm.

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.

Cucumbers remain cool to the touch even in heat.

Used in English since the 18th century.