a female who has the same parents with another person, or who has one of them only. in the latter case, she is more definitely called a half sister. the correlative of brother.-a woman who is closely allied to, or assocciated with, another person, as in the sdame faith, society, order, or community.-one of the same kind, or of the same condition; -- generally used adjectively; as, sister fruits.-to be sister to; to resemble closely.