- 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.
Origin: 20th-c. revival of OE, a relative: see sib and amp; -ling
Used by arrangement with John Wiley & Sons, Inc.
Origin: Middle English, from Old English, from sibb, kinsman; see sib.
sibling - Medical Definition