definition of
sister

[1] #1 sister n. [sis] a female person who has the same parents as another person; "my sister married a musician". wn

[2] #2 sister n. [Sister] (Roman Catholic Church) a title given to a nun (and used as a form of address); "the Sisters taught her to love God". wn

[3] #3 sister n. a female person who is a fellow member of a sorority or labor union or other group; "none of her sisters would betray her". wn

[4] #4 sister n. [baby, babe] (slang) sometimes used as a term of address for attractive young women. wn