Hottub and Hip bath

Hip bath and hottub are semantically related. In some cases you can use "Hip bath" instead a noun "Hottub".

Hip bath noun - A bathtub in which your buttocks and hips are immersed as if you were sitting in a chair and you bathe in a sitting position.

Hottub and hip bath are semantically related. You can use "Hottub" instead a noun phrase "Hip bath".