There are plenty of synonyms for the phrase "keep one cool." Some include staying calm, maintaining composure, keeping one's head, remaining collected, and holding one's temper. Other applicable words and phrases include self-control, level-headedness, equanimity, and restraint. When things get heated, it can be challenging to keep one's cool, but using these synonyms can remind us of the importance of staying calm and composed. By staying level-headed and composed, we can prevent arguments and conflicts from escalating and effectively deal with the situation at hand. So, whether in personal or professional situations, keeping one cool is essential for navigating life's challenges with ease.