1) When a female (or a man, respectively) is repeatedly showered with a large amount of cum from several other males.
2) To take a bath in cum.
See also: Bukkake
"Florence had ran out of Johnson's so she decided to have a cum-bath."
A cum-bath is a favorite of true sluts. The whore allows herself to be drenched in hot cum from head to toe. If a slut is lucky she will get 10 to 15 men to shoot jizz in her hair, on her face and tits, all over her wet used pussy, and on her dirty ass.
Kathy got a nice hot cum-bath last night. When i got home from work she was lying naked on the bed surrounded by men she had met at a bar. Her face was already sticky with cum and she was begging for more. She was rubbing jizz into her tits and calling herself a cumslut.