The Collaborative International Dictionary of English v.0.48:

Toupee \Tou*pee"\ (?; 277), Toupet \Tou*pet"\ (?; 277), n. [F.
   toupet, dim. of OF. top a tuft; of Teutonic origin, and akin
   to E. top. See Top apex, and cf. Topet.]
   [1913 Webster]
   1. A little tuft; a curl or artificial lock of hair.
      [1913 Webster]

   2. A small wig, or a toppiece of a wig.
      [1913 Webster]

            Her powdered hair is turned backward over a toupee.
                                                  --G. Eliot.
      [1913 Webster]

WordNet (r) 3.0 (2006):

toupee
    n 1: a small hairpiece to cover partial baldness [syn: toupee,
         toupe]