Real Dictionary

tummler in American English
an entertainer or social director whose function is to stimulate participation by the guests, as at a resort on the borscht circuit
noun: a male entertainer, as formerly employed by resorts in the Catskill Mountains, who combined the duties of a comedian, activities director, and master of ceremonies to keep the guests amused throughout the day

tummler in British English
noun: a comedian or other entertainer employed to encourage audience participation or to encourage guests at a resort to take part in communal activities