sibling
nounUK /ˈsɪblɪŋ/
US /ˈsɪblɪŋ/
A sibling is a brother or sister.
My little sister is my favorite sibling.
OTHER MEANINGS
2. A brother or sister sharing at least one parent.
She has three siblings from her father's second marriage.
3. In biology, offspring from the same parents in a family group.
The two lion cubs are siblings from the same litter.
4. A person or thing closely related to another in origin or kind.
These two languages are siblings, both descended from Latin.