There is no specific term in the English language to describe a relationship between you and your nephew's wife. Most people would say you are not related. If you must use some phrase, the phrase "my nephew's wife" is probably the clearest and most direct.
There is no relationship term to describe your nephew's wife.
You are not related to your nephew's wife.
Your nephew's wife is not related to you. To refer to her, you would call her, "My nephew's wife."
The English language has no specific term for the wife of a nephew. If you need to refer to her other than by her name, you would call her "my nephew's wife."
You probably aren't related at all. You must share a common ancestor to be related.
Ninec in law
You are her great aunt or uncle.
Some would just call her your niece(by marriage).
Great nephew
Nephews are the sons of your brother or sister. Therefore nephews who are not brothers to each other are first cousins to each other.
He is their Uncle and they are nieces and nephews.
Second cousins.
Your brother-in-law's children are your nephews and nieces.
Your brother's children would be your nieces and nephews.
If it's your sister then your sister, if it's your brother's wife then you sister-in-law
The English language has no relationship name for the wife of your great niece or great nephew.
Your sister's husband is your children's uncle. They are his nieces and nephews.
You would call your wife's elder brother's wife "sister-in-law."
Your borther-in-law is your grandchildren's great uncle. They are his great nieces and great nephews.
You do not have a niece-in-law. Some of your nieces and nephews are that because they are the children of your husband's siblings. They are your nieces and nephews and you and your husband together are their "aunt and uncle."