3rd Cousins
They are your nieces and nephews.
The children of your husband's sister are your nieces or nephews, and you are their aunt, just as he is their uncle.
He is their Uncle and they are nieces and nephews.
Your sister's husband is your children's uncle. They are his nieces and nephews.
Your sister's husband is your brother-in-law. Your brother-in-law's brother is not related to you and neither are his children. But he is your sister's brother-in-law and his children are your sister's nieces and nephews.
Your husband's sister's kids are referred to as your nieces and nephews by marriage. More specifically, you can call them your "nieces" if they are girls and "nephews" if they are boys.
Even thought you not related in genealogy sense you are related by marriage and you can say they are newphew and nieces in law.
You can refer to your sister's children as your nieces and nephews. If your sister has daughters, they are your nieces, and if she has sons, they are your nephews. Collectively, you can call them your nieces and nephews or simply refer to them as your sister's kids.
The daughters of your sister are your nieces.
When a couple is married and the wife has nieces who are daughters of her brothers or sisters, those nieces are also the nieces of her husband. So your great grandmother's sister's husband could have great nieces who are related to you and also great nieces who are not related to you.Note that your great grandmother's sister is your great great aunt.The great nieces who are related to you are the grandchildren of the siblings of your great great aunt.Those could be your:parentauntfirst cousins, once removedsecond cousins, once removed
They are your nieces and nephews and not your cousins
I can give you several sentences.My nieces are coming for a visit.Are those girls your nieces?Nieces are the daughters of your brother or sister.