a type of Italian comedy developed in the 16th through 18th cent. and employing a stereotyped plot, improvised dialogue, and stock characters such as Pantaloon, Harlequin, and Columbine
See commedia dell'arte in American Heritage Dictionary 4
(kə-māˌdē-ə dĕl-ärˈtē, -tĕ, -mĕdˌē-ə)
noun
A type of comedy developed in Italy in the 16th and 17th centuries and characterized by improvisation from a standard plot outline and the use of stock characters, often in traditional masks and costumes.