The phrase "on a cloud" is commonly used to describe a feeling of happiness, contentment, or tranquility. However, there are many other synonyms for this phrase that can be used to convey similar emotions. For instance, one could say they feel "over the moon," "elated," "ecstatic," or "blissful." Other options include "floating on air," "in seventh heaven," or "on top of the world." Whatever the phrase used, it is clear that being "on a cloud" is a state of mind that represents pure joy and peace.