sibling
//ˈsɪblɪŋ//
Noun
siblingSingular
siblingsPlural
1
A brother or sister; a person who shares one or both parents with another.
I have two siblings: an older brother and a younger sister.
2
A person or thing closely related to or resembling another.
This new smartphone is a sibling of the previous model, sharing many of the same features.