The word "most gladsome" implies extreme joy and happiness. Some antonyms that could be used to describe the opposite of "most gladsome" include despondent, woebegone, mournful, disconsolate, sorrowful, miserable, and melancholy. These words describe a feeling of sadness, loss or grief, rather than joy. Another antonym for "most gladsome" could be "dreary" or "gloomy," which suggest a lack of brightness or cheerfulness. In contrast, "most gladsome" suggests a feeling of bright and energetic optimism. Regardless of the antonyms used, it is always important to maintain a positive attitude and strive for happiness and joy in life.