Boiling over is a phrase that signifies intense anger or agitation, and many language experts suggest that antonyms for this phrase are "calm" or "composed." Some other possible antonyms for boiling over could be "tranquil," "relaxed," "placid," "serene," or "peaceful." These words represent a state of mind that is in sharp contrast with boiling over, which suggests frustration and loss of control. By using these antonyms, one can effectively convey a sense of calmness and composure in a situation instead of showing intense anger or agitation. Being able to use the right antonym is crucial to expressing one's emotions and creating a better communication experience with others.