noun
Polite term for one's spouse's mother. Used both as a form of address and when referring to her in conversation.
お義母さんは料理がとても上手です。
My mother-in-law is very good at cooking.
お義母さん、これ、つまらないものですが。
Mother-in-law, this is just a little something for you.
noun
Polite term for a woman who raises a child as her own, though not the biological mother. Less common than the mother-in-law sense.
彼女は幼い頃からお義母さんに育てられた。
She was raised by her foster mother from a young age.
noun
Polite term for the wife of one's father who is not one's biological mother. Used in address and reference.
お義母さんとは最初はぎこちなかったけど、今は仲良しです。
At first things were awkward with my stepmother, but now we get along well.