mother-in-law
foster mother
step mother
義母と食事に出かけた。
I went out for a meal with my mother-in-law.
義母の誕生日にプレゼントを贈った。
I gave a present for my mother-in-law's birthday.
義母とは良好な関係を築けていると思う。
I think I have built a good relationship with my mother-in-law.