The women whom a man is forbidden to marry. (مَحارِمُ)
أصول الفقه
المعنى الاصطلاحي :
A woman who is permanently forbidden to marry a certain man because of kinship, nursing, or marriage ties between them.
التعريف اللغوي المختصر :
"Mahaarim" (sing. mahram): that which has been made haram by Allah and cannot be made lawful. It is said: He is her "mahram" if it is unlawful for him to marry her. Also, a woman is called "mahram" in reference to a person when it is unlawful for her to marry that person.