By Nieces and Nephews?

In the lineal kinship system used in the English-speaking world, a niece or nephew is a child of the subject's sibling or sibling-in-law. The converse relationship, the relationship from the niece or nephew's perspective, is that of an aunt or uncle.

Is there one word for nieces and nephews?

Nibling is a gender-neutral term used to refer to a child of one's sibling as a replacement for "niece" or "nephew".

What do you mean by nephews and nieces?

A nephew is the son of someone's brother or sister. A niece is the daughter of the person's brother or sister. To the nephew or niece, the person is their uncle or aunt.