sib \sib\ si^b, n. as. sibb alliance, gesib a relative.
   root289. see gossip.
   1. a blood relation. obs. --nash.
      1913 webster

   2. a sibling.
      pjc
see also:
gossip sibling 

sib \sib\, a.
   related by blood; akin. obs. or prov. eng.  scot. --sir w.
   scott.
   1913 webster

         your kindred is but . . . little sib to you. --chaucer.
   1913 webster

         he is no fairy birn, ne sib at all
         to elfs, but sprung of seed terrestrial. --spenser.
   1913 webster

sib
     n 1: a person's brother or sister syn: sibling
     2: one related by blood or origin; especially on sharing an
        ancestor with another syn: blood relation, blood
        relative, cognate
see also:
sibling blood relation blood relative cognate 

66 moby thesaurus words for "sib":
   affiliated, agnate, akin, allied, ancestry, avuncular, blood,
   blood relation, blood relative, clansman, closely related, cognate,
   collateral, collateral relative, congeneric, connections,
   consanguine, consanguinean, consanguineous, distaff side,
   distant relation, distantly related, enate, family, flesh,
   flesh and blood, folks, foster, friendly, german, germane, kin,
   kindred, kinfolk, kinnery, kinsfolk, kinsman, kinsmen, kinswoman,
   kith and kin, matrilateral, matrilineal, matroclinous,
   near relation, next of kin, novercal, of the blood, patrilateral,
   patrilineal, patroclinous, people, posterity, receptive, related,
   relations, relatives, sibling, spear kin, spear side, spindle kin,
   spindle side, sword side, tribesman, uterine, uterine kin,
   well-disposed

sib
     service independent building block in