Other forms: cotillions
A cotillion is either a dance that originated in France in the 18th century or a ball where debutantes are presented.
The earliest sense of this word goes back to France and the 1700's: this cotillion was a dance with complicated steps and movements. This was a quick, lively sort of dance that must have been a lot of fun back in the day. More recently, a cotillion became the name of a ball (dance event) in the United States. Debutantes — young society ladies — are presented at cotillions. So when you think of cotillions, think of fancy-schmancy dances and high society.