What is 'sister' in Chinese?

Chinese has two Words for sister.

If the sister is older than you (or is older than the person being addressed), sister is 姊姊. This is also written 姐姐 some times. It is pronounced jie3jie in Hanyu Pinyin.

If the sister is older than you (or is the younger sister in a family), sister is 妹妹. This is pronounced mei4mei in Hanyu Pinyin.