When you need to describe someone breathing heavily, there are a variety of synonyms you can use to add depth and variety to your writing. Instead of simply saying "breathe heavily," consider phrases such as panting, gasping for air, wheezing, huffing and puffing, puffed out, out of breath, or short of breath. Each of these phrases conveys a slightly different nuance and can help to create a more vivid picture in the reader's mind. Whether you are describing a character in a novel or writing about someone in real life, using a range of synonyms for "breathe heavily" can make your writing more engaging and descriptive.