Definitions for bubble bath
Random House Webster's College Dictionary
a crystal, powder, or liquid preparation that foams in, scents, and softens bathwater.
a bath with such a preparation added to the water.
Origin of bubble bath:
a bath in which you add something to foam and scent the bath water
A bath in which an additive is poured directly into the water that creates bubbles.
A soap-based product to be added to a bath to create bubbles.