1. (n.) 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.

2. (n.) A woman who is closely allied to, or associated with, another person, as in the same faith, society, order, or community.

3. (n.) One of the same kind, or of the same condition; -- generally used adjectively; as, sister fruits.

4. (v. t.) To be sister to; to resemble closely.