The antonyms for the word "more clownish" can be words like serious, mature, sensible, professional, or sophisticated. These words are used to describe someone who is formal and respectable, and not silly or childish. When someone is described as "more clownish", it means they are acting in a way that is foolish or overly playful. But using the antonyms can help you describe someone who is having fun but not taking things to an extreme. There is a difference between being lighthearted and playful and being completely clownish, and using antonyms can help you make this distinction.