Sibling

A sibling is a brother or sister, someone who has the same parents as you. It can refer to either gender.

“Sibling” comes from Old English “sweostor” (sister) and an old root “sib,” meaning kin or relatedness, plus the diminutive “-ling.” It was rare for centuries and became common only in the 20th century as a neutral term. The ‘sib’ part survives in ‘sibling’ and in the idea of kinship.