When it comes to expressing the idea that one is comfortable, there are multiple synonyms to choose from. These synonyms range from informal to formal language and can be used in a variety of settings. Some informal synonyms include "feel at ease," "be relaxed," or "feel cozy." More formal synonyms may include "experience contentment," "be at peace," or "be in a tranquil state." Other possibilities may include "enjoy ease," "feel comfortable," or "have a sense of security." Whether you are writing a formal letter or chatting with friends, using these various synonyms can help convey your comfort level in a more expressive and nuanced way.