cool as a cucumber

Adjective

not-comparable

(simile) Calm and composed even in difficult or frustrating situations; self-possessed.

Japanese Meaning

（比喩的に）どんな困難な状況でも冷静さを失わず、平常心を保っている状態を表す / 困難な場面でも落ち着いて対応できる様子

Even while the meeting descended into chaos, Sarah remained cool as a cucumber, calmly outlining the next steps.

会議が混乱に陥ったときでも、サラは冷静沈着で次の手順を落ち着いて説明した。

Sense（1）

(simile) Calm and composed even in difficult or frustrating situations; self-possessed.

Even during the elections, Josh was as cool as a cucumber.