Date: circa 1881 the double-walled fluid-filled sac that encloses and protects the fetus in the womb and that breaks releasing its fluid during the birth process
BAG OF WATERS
Meaning of BAG OF WATERS in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012