/keuh til"yeuhn, koh-/ , n.
1. a formal ball given esp. for debutantes.
2. a lively French social dance originating in the 18th century, consisting of a variety of steps and figures and performed by couples.
3. any of various dances resembling the quadrille.
4. music arranged or played for these dances.
5. a formalized dance for a large number of people, in which a head couple leads the other dancers through elaborate and stately figures.
[ 1760-70; cotillon kind of dance, in OF: petticoat, equiv. to cote COAT + -illon dim. suffix ]