a professional clown employed to entertain a king or nobleman in the Middle Ages
"The medieval court entertained guests when their royal jester told jokes and performed acrobatics."
One who jests, jokes or teases.
"The old court jester never stopped joking until even the stern king laughed at his silly antics."
A surname.
"The town's annual festival was organized by a man named Jester, who had served as its mayor for twenty years."