妹 - younger sister

younger brother and sister

cousin (female)

sister-in-law (spouse's younger sister or younger brother's wife)

younger sister

sisters

pogo sisters; women who have had sex with the same man

threesome including two women who are sisters

younger daughter

protegee; someone who one considers as a younger sister

the husband of one's younger sister

younger sister

half-sister (different father); half-sisters