'bathtub' originates from English, specifically the words 'bath' and 'tub', where 'bath' meant 'a washing or immersion of something in water' and 'tub' referred to 'a large container'.

'bathtub' evolved from the combination of the words 'bath' and 'tub' in English, maintaining its meaning over time.

Initially, it meant 'a container for bathing', and this meaning has largely remained the same in modern usage.