noun, feminine/ɡʁə.nuj də be.ni.tje/plural: grenouilles de bénitier
a Holy Mary, a zealot, a God botherer, a Jesus freak, a Bible thumper (an excessively pious woman, a woman who spends a lot of a time at church)
Synonyms: cul-bénit, punaise de sacristie
Literally, “stoup frog”.