The Collaborative International Dictionary of English v.0.48:

Chignon \Chi"gnon\, n. [F., prop. equiv. to cha[^i]non link, fr.
   cha[^i]ne chain, fr. L. catena Cf. Chain.]
   A knot, boss, or mass of hair, natural or artificial, worn by
   a woman at the back of the head.
   [1913 Webster]

         A curl that had strayed from her chignon. --H. James.
   [1913 Webster] Chigoe

WordNet (r) 3.0 (2006):

chignon
    n 1: a roll of hair worn at the nape of the neck