Source : Webster's Revised Unabridged Dictionary (1913)

Topknot \Top"knot`\, n.
   1. A crest or knot of feathers upon the head or top, as of a
      bird; also, an orgamental knot worn on top of the head, as
      by women.

            A great, stout servant girl, with cheeks as red as
            her topknot.                          --Sir W.
                                                  Scott.

   2. (Zo["o]l.) A small Europen flounder ({Rhoumbus
      punctatus}). The name is also applied to allied species.

Source : WordNet®

topknot
     n 1: headdress consisting of a decorative ribbon or bow worn in
          the hair
     2: showy crest or knot of hair or feathers