The Collaborative International Dictionary of English v.0.48:

D'ebutant \D['e]`bu`tant"\, n.; fem. D'ebutante
\D['e]`bu`tante"\ [F., p. pr. of d['e]buter to have the first
   throw, to make one's d['e]but. See D['e]but.]
   A person who makes his (or her) first appearance before the
   public.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

D'ebutante \D['e]`bu`tante"\, fem. n.
   A young woman making her first appearance in society,
   especially one who is one of the honorees at a debutante
   cotillion. See cotillion[4].
   [PJC]

WordNet (r) 3.0 (2006):

debutante
    n 1: a young woman making her debut into society [syn:
         debutante, deb]