Definition of sib in English:



  • 1Zoology
    A brother or sister; a sibling.

    • ‘The latter three species are referred to collectively as siblings, abbreviated as sib.’
    • ‘In contrast, males that encountered mole-rat scent behaved differently, in several ways, to their sibs that encountered predator scent (at least in high-markers).’
    • ‘In nine cases only one of two same-sex siblings became a breeder; in eight of these it was the heaviest of the two sibs (p =.019, binomial test, n = 9).’
    • ‘This allowed experimental chicks to be more successful at competing with sibs (who often had been raised by parents singly or in pairs) when they were returned to their natal nest after the hand-rearing period.’
    • ‘The more fleet-footed of two chinstrap penguin sibs is the fitter; being the bolder signaler, it is recognized by the parent as being more likely to survive.’
    group of families, sept, gens
    View synonyms
  • 2Anthropology
    A group of people recognized by an individual as his or her kindred.

    • ‘Therefore, many researchers expect to see just the sort of discriminating parental investment reported by Mann - behavior that favors more vigorous offspring over their less healthy sibs.’


Old English, related by birth or descent of unknown origin. Sense 1 dates from the early 20th century.

Definition of SIB in English:


  • Securities and Investment Board, a regulatory body that oversees London's financial markets.