Avant Garde:

In general, the term means experimental, innovative, at the forefront of a literary or artistic trend or movement. Avant garde art and literature revolts against tradition and convention. In terms of theater history, however, the term originated in France in the 1920s. Avant garde playwrights rejected realism and tried to stimulate the imagination of the spectator. They emphasized the role of the author as an artist with a vision, and the role of the director as an interpreter of that vision. They also stressed the importance of bodily movement and vocal expression in the work of the actor. The avant garde dramatists wished to educate a new type of spectator, who would become attached to one specific playhouse and demand of it more than mere entertainment.

The Oxford Companion to the Theater, Fourth Edition