Bathtub and Hip bath

Bathtub noun - A relatively large open container that you fill with water and use to wash the body.

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

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.

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