The cotillion is a type of patterned social dance that originated in France in the 18th century.
Its name, from French cotillon, "petticoat", reflected the flash of petticoats as the changing partners turned. The cotillion, of repeated "figures" interspersed with "changes" of different figures to different music, was one of many contredanses where the gathered participants were able to introduce themselves and to flirt with other dancers through the exchange of partners within the formation network.
In British usage, cotillion has disappeared, save in French or historical contexts.
Cotillions were introduced in London about 1766 by French dancing masters.
They came to America in about 1772, where, in some places, they are still practiced.