The antonyms for the word "Good-humoredly" include words such as sullenly, grumpily, irascibly, morosely, and sourly. These words depict a lack of cheerfulness, positivity, and humor. Good-humoredly means to be in a cheerful and upbeat mood, which is quite the opposite of its antonyms. The use of antonyms can create contrast and help to emphasize a particular emotion or tone in a sentence. For instance, instead of saying, "She always greets us good-humoredly," one could say, "She often greets us sullenly," to paint a more gloomy picture. In summary, antonyms help to convey meaning by highlighting the opposites of words.