babymother 
noun
The mother of one or more of a man’s children, who is not his wife or current partner.If he is a married man, what sort of incriminating things could his babymother be seeing at his house?...
- However just like my babymother they all want the World and are usually not prepared to do anything about it themselves.
- Eventually, one of his babymothers got tired of having to raise her son off her small paycheck and took him to court for not financially supporting the child.
Origin
1960s: from baby + mother, after babyfather; originally in Caribbean English.