Performances that include trained animal acts or exhibitions of human skill and daring, or both. Circuses usually include a trained, traveling company or troupe of performers, various animals, and their equipage. The term "circus" refers to the circular arena surrounded by tiers of seats below which the performance occurs in a circular area called the "ring."
Source: Art & Architecture Thesaurus
http://vocab.getty.edu/page/aat/300069235
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