Noun
Someone's niece's husband
Someone's nephew's husband (where same-sex marriage is recognised)
Someone's sibling's son-in-law
Someone's brother's son-in-law. (fraternal nephew-in-law)
Someone's sister's son-in-law. (sororal nephew-in-law)
Someone's spouse's sibling's son-in-law
Someone's wife's brother's son-in-law.
Someone's wife's sister's son-in-law.
Someone's husband's brother's son-in-law.
Someone's husband's sister's son-in-law.
(rare) Someone's spouse's nephew.
Someone's husband's nephew. (Usually called a nephew.)
Someone's wife's nephew. (Usually called a nephew.)
Source: en.wiktionary.org