Sib /(sĭb)/

Sib

n.
  1. A blood relation. [Obs.]
  2. a sibling.

Sib

a.
  1. Related by blood; akin. [Obs. or Prov. Eng. & Scot.]
    Your kindred is but . . . little sib to you.
    [He] is no fairy birn, ne sib at all To elfs, but sprung of seed terrestrial.