noun Date: 1813 an automatic escape or relief valve (as for a steam boiler), an outlet for pent-up energy or emotion, something that relieves the pressure of overcrowding
SAFETY VALVE
Meaning of SAFETY VALVE in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012