IPA: /ˈbæθtʌb/
KK: /ˈbæθtʌb/
A large container filled with water for people to wash themselves in, usually found in a bathroom.
After a long day, I love to relax in a warm bathtub.
Bathtub → It is formed from "bath" (from Old English *baþ*, meaning a washing or soaking) and "tub" (from Middle English *tubbe*, meaning a container or vessel). The word "bathtub" refers to a container used for bathing or soaking in water.
Think of a 'washing' ('bath') place that is a 'container' ('tub') for soaking — that's what a bathtub is.
No commonly confused words.