noun
toilet sandals; bathroom sandals
Sandals worn exclusively in the toilet or bathroom, typically found in Japanese homes or shared facilities to keep the area hygienic.
トイレに入るときは便所サンダルに履き替えてください。
Please change into the toilet sandals when you enter the restroom.
スリッパ are general indoor slippers, while 便所サンダル are specifically for toilet use and are often kept at the bathroom entrance.
Compound of 便所 (toilet) and サンダル (sandals), a straightforward modern term.