zǐ​mèi

sisters

姊妹 zǐ​mèi
sisters noun
older and younger biological or familial sisters

The two sisters look very much alike.

sister (affiliated) noun
entities or institutions sharing a close bond or origin, such as sister schools or cities

These two universities are sister schools.

Frequency

Movie subtitles
2.35 per million appears in 1% of films
Written text
3.84 per million

Sources

Definitions
CC-CEDICT