before 900;Middle Englishsib(e), sibb(e), Old Englishsib(b) (orig. adj.); cognate with Old Norsesifjar (plural) relatives, Old Frisiansib (adj.), sibba (noun), Middle Dutchsibbe (noun and adj.), GermanSippe kin; cf. gossip
British Dictionary definitions for sib
sib
/sɪb/
noun
1.
a blood relative
2.
a brother or sister; sibling
3.
kinsmen collectively; kindred
4.
any social unit that is bonded by kinship through one line of descent only
Word Origin
Old English sibb; related to Old Norse sifjar relatives, Old High German sippa kinship, Latin suus one's own; see gossip