The antonyms for the word "more lightsome" are plenty, as the term is considered optimistic, joyous, or bright. Some possible antonyms or opposite words could be heavier, darker, gloomier, morose, somber, depressing, sullen, disheartening, or downbeat. The word "lightsome" implies a sense of lightness or buoyancy, suggesting pleasantness and cheerfulness. This makes it easy to think of antonyms that embody the opposite sentiment, with words that would evoke a feeling of heaviness and gloom instead. Ultimately, understanding the antonyms for certain words can help one better appreciate and recognize the nuances of language.