noun
toilet seat
Refers to the seat of a toilet, typically in a Western-style toilet.
寒い日は便座が冷たくてびっくりする。
On cold days, the toilet seat is so cold it surprises me.
便座を上げてから用を足してください。
Please lift the toilet seat before using the toilet.
Compound of 便 (ben, 'excrement' or 'convenience') and 座 (za, 'seat'). The spelling 便坐 is a rare variant using the character 坐, an older form of 座.