nieces

noun
  1. 1

    A daughter of one’s sibling, brother-in-law, or sister-in-law; either the daughter of one's brother ("fraternal niece"), or of one's sister ("sororal niece").

    My niece just celebrated her 15th birthday.

Source: https://en.wiktionary.org/wiki/niece, https://en.wiktionary.org/wiki/nieces