When it comes to maintaining a calm demeanor, there are plenty of ways to say "keep cool." Some popular synonyms include "remain composed," "stay collected," "calm down," "relax," and "take it easy." There are also some more colloquial phrases, such as "don't lose your cool," "keep your cool head," and "keep a level head." Whatever phrase you use, the aim is the same: to stay centered in the face of difficult or tense situations. Keeping cool is an important skill in both personal and professional settings, and there is no shame in needing to remind oneself to stay calm and collected.