keep a stiff upper lip
US /kiːp ə stɪf ˈʌpər lɪp/
UK /kiːp ə stɪf ˈʌpər lɪp/

1.
冷静さを保つ, 感情を表に出さない, 我慢する
to remain brave and unemotional in a difficult or upsetting situation
:
•
Despite the bad news, she managed to keep a stiff upper lip.
悪い知らせにもかかわらず、彼女は冷静さを保った。
•
The soldiers were told to keep a stiff upper lip during the difficult mission.
兵士たちは困難な任務中も冷静さを保つように言われた。