parapet
noun [ C ] uk/ˈpær.ə.pet/ us/ˈper.ə.pet/
（屋顶、桥等旁边的）矮护墙，女儿墙
a low wall along the edge of a roof, bridge, etc.
Idiom
put your head over/above the parapetidiom UK 大胆说出某人的想法
to be brave enough to state an opinion that might upset someone