Looks sullen can be replaced with a contrasting word, which will convey an entirely different meaning. Some antonyms of sullen include cheerful, optimistic, bright, and optimistic. A cheerful person has a bright, lively, and positive personality that spreads happiness to those around them. Optimistic individuals have a positive outlook, regardless of their situation or circumstances. Bright people exude lightness, intelligence, and enthusiasm, while optimistic individuals see the best in everything. By selecting the appropriate antonym of sullen, one can help to enhance communication, change tone and mood, and de-escalate negative emotions. In this way, choosing the right word can go a long way in communicating our message effectively.