Mellifluousnesses, which refers to a sweet or pleasant sound, can have many antonyms. Some words that could be used as antonyms for mellifluousnesses may include unpleasant, harsh, grating, discordant, or cacophonous. These antonyms describe sounds that are jarring or harsh to the ear, rather than sweet and soothing. Another possible antonym for mellifluousnesses is monotony, which refers to a lack of variety or interest in sound. While mellifluousnesses may evoke feelings of comfort and warmth, their antonyms may instead elicit negative emotions such as discomfort or irritation.