Antonyms for the word "out-bursts" include composed, tranquil, peaceful, restrained, serene, and calm. When we experience an outburst of emotion, we lose our composure and become agitated. However, being tranquil means being free from disturbance or agitation. Similarly, peacefulness is a state of calm and quietness which is opposite to outbursts. Restraint means having control over one's emotions or actions and avoiding outbursts. Serenity is a state of being calm and still, without any disturbance or disturbance. Lastly, being calm is the opposite of outbursts as it means having a peaceful and composed state of mind even during challenging situations.