Jester
Part of speech: noun
Definition: one who jests, jokes or mocks a person in bright garb and fool's cap who amused a mediaeval royal court.
Clown
Part of speech: noun
Definition: A performance artist often associated with a circus and typically characterised by bright, oversized clothing, a red nose, face paint, and a brightly colored wig and who performs slapstick.A person who acts in a silly fashion.
Part of speech: verb
Definition: (also clown about (British) or clown around) To act in a silly fashion.
Example sentence: But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown.