noun
biological mother; birth mother; real mother
Refers to one's biological mother, as opposed to a stepmother, adoptive mother, or mother-in-law. Often used in formal or legal contexts.
彼女は実母の顔を知らない。
She doesn't know the face of her biological mother.
実母と養母の両方と仲が良い。
I get along well with both my birth mother and my adoptive mother.