Bitter chocolate, also known as unsweetened chocolate, has a distinct taste profile that is sometimes described as acidic, earthy, or even smoky. However, there are several synonyms for bitter chocolate that can be used to add some diversity to your writing. Some options include dark chocolate, which is a less intense version of bitter chocolate, cacao or cocoa, which both refer to the raw ingredient used to make chocolate, and baker's chocolate, which is a form of bitter chocolate specifically designed for baking. Additionally, you may also consider using synonyms such as chocolate liquor or pure chocolate to refer to the raw chocolate before it's processed with other ingredients.