Nibter is a term for a nonbinary sibling.
Sibling refers to someone born of the same parents, whereas, nibter refers to someone born of the same parents who is nonbinary, genderqueer, or agender.
Male sibling: Brother
Female sibling: Sister
Nonbinary sibling: Nibter
Synonym: sibling
Antonyms: sister, brother
My brother ate my cookie, my sister drank my milk, & my nibter stole my tea.
I have one nibter & two sisters.
My nibter is so sweet; they gave me half of their brownie.