- The definition of a sibling is a person who shares the same parents as you.
An example of a sibling is the little boy born to your mother and father right after you. He is your brother and your sibling.
sibling definition by Webster's New World
Origin: 20th-c. revival of Old English a relative: see sib and amp; -ling
sibling definition by American Heritage Dictionary
Origin: Middle English, from Old English, from sibb, kinsman; see sib.
sibling - Medical Definition