The word "Mumpish" is commonly used to describe someone who is sulky, moody or irritable. Antonyms for this word would include feelings of cheerfulness, happiness, and contentment. Words like "cheerful," "optimistic," and "jolly" would be perfect antonyms for the negative connotations of mumpish. Other antonyms could include "calm," "tranquil," and "serene," as mumpish often implies a state of agitation or irritability in someone's demeanor. By focusing on these more positive antonyms, it is possible to help someone shift away from mumpish tendencies and move towards a more happy, stress-free life.