Wiktionary
niece-in-law
n. 1 daughter-in-law of someone's brother. 2 Daughter-in-law of someone's sister. 3 Daughter-in-law of someone's brother-in-law. 4 Daughter-in-law of someone's sister-in-law. 5 (context rare English) niece of someone's husband. (Usually called a niece.) 6 (context rare English) Niece of someone's wife. (Usually called a niece.) 7 Wife of someone's nephew.