JESTER

n. prankster, joker, one who makes jokes; one who works as a clown or entertainer (especially at a medieval court)

A jester, joker, fool or buffoon is a specific type of entertainer mostly (but not always) associated with the Middle Ages. Jesters typically wore brightly colored clothing in a motley pattern. Their hats, sometimes called the cap ’n bells, cockscomb (obsolete coxcomb), were especially distinctive; made of cloth, they were floppy with three points (liliripes) each of which had a jingle bell at the end. The three points of the hat represent the asses' ears and tail worn by jesters in earlier times. Other things distinctive about the jester were his incessant laughter and his mock scepter, known as a bauble or maharoof.
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Noun
1. a professional clown employed to entertain a king or nobleman in the middle ages
(synonym) fool, motley fool
(hypernym) clown, buffoon, merry andrew
(derivation) joke, jest

(n.)
A person addicted to jesting, or to indulgence in light and amusing talk.
  

(n.)
A buffoon; a merry-andrew; a court fool.
  

To dream of a jester, foretells you will ignore important things in looking after silly affairs.