older brother and younger sister
sister-in-law (spouse's younger sister or younger brother's wife); younger stepsister; younger adopted sister; non-blood-related younger sister
younger brother and sister
brothers and sisters; siblings
half-sister (younger, different mother)
biological younger sister
sisterly love; affection between sisters
threesome including two women who are sisters
women who have had sex with the same man; (lit.) pole sisters
half-sister (different father); half-sisters
little sister; younger sister; my younger sister; I; me
pogo sisters; women who have had sex with the same man
companion (sister) volume (to); sequel (to)
sister chromatid exchange
affiliated company; sister company
sister language; related language; cognate
sister group; sister taxon
one's deceased younger sister