There are many different synonyms for the phrase "kept calm". Some of the most common options include maintaining composure, staying collected, remaining tranquil, keeping cool, and holding one's nerve. Other possibilities include keeping one's head, staying level-headed, maintaining equanimity, remaining serene, and staying unflappable. No matter which synonym one chooses to use, the underlying meaning remains the same: the person in question is able to resist the urge to panic or otherwise lose control in a difficult or stressful situation. This ability to remain calm is often seen as a desirable trait, as it allows individuals to think clearly, make sound decisions, and avoid making impulsive or reckless choices.