From Longman Dictionary of Contemporary Englishclownclown1 /klaʊn/ ●○○ noun [countable] 1 
BOAPFUNNYsomeone who wears funny clothes, a red nose, bright make-up on their face etc, and does silly things to make people laugh, especially at a circus2 FUNNYsomeone who often makes jokes or behaves in a funny way Frankie’s a bit of a clown.class clown (=someone in a school class who behaves in a funny or silly way)3 STUPID/NOT SENSIBLEa stupid or annoying person I can’t understand what she sees in that clown.
BOAPFUNNYsomeone who wears funny clothes, a red nose, bright make-up on their face etc, and does silly things to make people laugh, especially at a circus2 FUNNYsomeone who often makes jokes or behaves in a funny way Frankie’s a bit of a clown.class clown (=someone in a school class who behaves in a funny or silly way)3 STUPID/NOT SENSIBLEa stupid or annoying person I can’t understand what she sees in that clown.Examples from the Corpus
clown• Howie is a well-known writer and clown.• Her orange-red hair was worn bouffant, and her orange lipstick made her look like a small circus clown.• Maguire, matter of fact, is much like the class clown who sits three bar stools away watching the game.• Specimens of this anemone have been seen with as many two dozen clown anemonefish nestled among their tentacles.• A cannibal I knew refused to eat clowns.• Some clown cut in front of me on the freeway this morning and almost hit me.• Only two or three clowns dressed up and nothing much took place.• The twins, at almost eleven, were clowns, especially Shaw, who was beginning a career as the family subversive.class clown• The teacher was coming to me and saying Casey was like a class clown.• Maguire, matter of fact, is much like the class clown who sits three bar stools away watching the game.• He caught her eye and beckoned curling his finger in the manner of a schoolmaster summoning the class clown.clownclown2 (also clown around/about) verb [intransitive] FUNNYto behave in a silly or funny way Stop clowning around!→ See Verb tableExamples from the Corpus
clown• He had no idea that people thought he was clowning.• Others spend the majority of their time clowning.• People riotously reel around here, fighting, fondling, tittering, clowning.• Stop clowning around and get back to work.• Harvey was clowning around pretending to be a gunman, which was his way of being sarcastic to me.• They are clowning for the camera.• But Garvey and Lucie had to clown more than before.Origin clown1 (1500-1600) Perhaps from French coulon “someone who settles in a new country”, from Latin colonus; → COLONY 