Other forms: siblings
A sibling is a brother or a sister — one word for both. Two siblings, my youngest sibling, sibling relationships.
English had no everyday word for this until the twentieth century, when scientists revived an Old English one because they needed a term without sex in it. It is still slightly technical: people say brothers and sisters in speech and siblings on forms.
1nounsiblingA brother or a sister.
“Do you have any siblings, or are you an only child?”
sibling is a family relation.
Revived about 1903 from Old English sibling, a relative, from sib, kinship. Gossip contains the same sib.
Old English
sibling — relative, a relation, kinsman
English, today
sibling
First use appears c. 1903, a modern revival of Old English sibling (“relative, a relation, kinsman”), equivalent to sib + ling. Compare Middle English siblynges, sib, sibbe (“relative; kinsman”), German Sippe. The term apparently meant merely kin or relative until the 20th century when it was applied in a way that aided the study of genetics, which led to its specialized use. For example, the OED has a citation in 1902 in which sibling must be defined for those who do not know the intended meaning.
Etymology from Wiktionary, CC BY-SA