Works from the 1950s and 1960s that were unique, unrehearsed events, often combining elements of theater, music, and the visual arts. Usually nonverbal, they may incorporate visual, tactile, and olfactory responses, chance, and audience participation. The term was coined by artist Allan Kaprow.
Source: Art & Architecture Thesaurus
http://vocab.getty.edu/page/aat/300047935
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