Auntie, but maybe if he is rude he may call you lady do not be offend if he is young and does this.
nephew
Yes, for a nephew is sister's son, brother's son, wife's brother's son, wife's sister's son, husband's brother's son, husband's sister's son
Your sister's son will call you his uncle, if you are a man, or his aunt, if you are a woman.
You call him your nephew. (pronouced nes-few)
Your sister's son is your nephew. You are his aunt or uncle.
If your sister had a son, then he is your nephew.
Your sister's son' son is her grandson. Your sister's grandson is your great nephew. You are his great uncle or great aunt.
Your father's sister's son (or daughter) is your first cousin.
You would call your sister's son your nefu and her daughter neice.
He would call her his aunt.
Your nephew.
Nephew