Bath is a noun that can mean many things, including a cleansing of the body, a contained liquid used to wash the body, a bathroom, bathtub, or a financial setback. One can take a bath, have a bath, or soak in a bath. The plural is baths. However, never does this word mean to have a bath or to wash. All forms are pronounced with the short a sound. A blood bath is a massacre where lots of blood is split, so much that people are soaked in it. This can be literal or figurative.
The verb to wash the body is bathe. Bathe can also be used to mean swimming leisurely. Its other forms include bathed, and bathing. One can be a bather. All of these forms are pronounced with the long a sound, such as is found in bait and ate.