noun.
A young woman making a formal debut into society.
The Century Dictionary and Cyclopedia
noun.
A woman appearing for the first time before the public or in society; specifically, an actress or a singer making her first appearance in public, or a young woman during her first season in society.
the GNU version of the Collaborative International Dictionary of English
A young woman making her first appearance in society, especially one who is one of the honorees at a debutante cotillion. See cotillion{4}.