Where does “電気風呂” come from?

電気風呂 (Japanese) comes from Japanese 風呂, from Japanese 室, from Middle Chinese 室.

電気風呂 (Japanese): vibration bath, a bath charged with an electric current strong enough to stimulate muscles and create a tingling sensation but low enough to be safe for healthy people

Definitions

vibration bath, a bath charged with an electric current strong enough to stimulate muscles and create a tingling sensation but low enough to be safe for healthy people

Ancestry of “電気風呂”, step by step

電気風呂 traces back through two separate lines of ancestry.

via Japanese 風呂

Step	Language	Word	Meaning
1	Japanese	風呂	bath; bathtub
2	Japanese	室	room
3	Middle Chinese	室	—

via Japanese 電気

Step	Language	Word	Meaning
1	Japanese	電気	electricity; electric light
2	Chinese	電氣	electricity; electrical power

Every word from Middle Chinese 室 →Every word from Japanese 室 →Every word from Japanese 風呂 →