The antonyms for the word "most jocose" could be serious, somber, dull, gloomy, or grave. Serious means not playful, humorous, or frivolous. Somber means dark or dismal, lacking brightness or cheer. Dull means lacking interest or excitement, not bright or sharp. Gloomy means dark or dim, lacking light or optimism. Grave means serious or solemn, often associated with death or tragedy. These antonyms describe the opposite of "most jocose," which means playful or humorous, and suggest a more somber or serious tone.