English to English
1. a female person who has the same parents as another person
my sister married a musician
2. (Roman Catholic Church) a title given to a nun (and used as a form of address)
the Sisters taught her to love God
3. a female person who is a fellow member of a sorority or labor union or other group
none of her sisters would betray her
4. (slang) sometimes used as a term of address for attractive young women
5. 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.
6. To be sister to; to resemble closely.