Source : Webster's Revised Unabridged Dictionary (1913)

Sisterhood \Sis"ter*hood\, n. [Sister + hood.]
   1. The state or relation of being a sister; the office or
      duty of a sister.

            She . . . abhorr'd Her proper blood, and left to do
            the part Of sisterhood, to do that of a wife.
                                                  --Daniel.

   2. A society of sisters; a society of women united in one
      faith or order; sisters, collectively. ``A sisterhood of
      holy nuns.'' --Shak.

            The fair young flowers . . . a beauteous sisterhood.
                                                  --Bryant.

Source : WordNet®

sisterhood
     n 1: the kinship relation between a female offspring and the
          siblings [syn: {sistership}]
     2: a religious society of sisters (especially an order of nuns)