In a lesbian couple, the nonbirth mother (partner of the birth mother) of a child, especially one who takes an equal role in mothering the child.
In polygamy, the relationship between one co-wife and another, in respect to their children.
In polygamy, a wife of one's father who is not one's mother; that is, co-wife of one's mother.
mamma; mother
In the southern United States, a black nanny employed to look after white children; or in the antebellum South, a female slave who was close to the household and looked after the children.