Atwitter means anxious, nervous, or excited. The antonyms for this word can help to describe a calm or serene state of mind. Some possible antonyms include composed, relaxed, calm, collected, and tranquil. These words also suggest a feeling of confidence, poise, and balance. Other antonyms for atwitter might include disinterested, apathetic, bored, or indifferent, indicating a lack of emotional investment or excitement. Antonyms are useful in expanding our vocabulary and helping us to express a range of emotions and states of mind. With a good selection of antonyms and synonyms, we can communicate more effectively and convey our thoughts and feelings with greater precision.