There are many different synonyms that can be used to describe the number 15. Some of the most common ones include "fifteen," "a dozen and three," and "a score and three." Other less common synonyms for the number 15 include "quindecim" (which is the Latin word for fifteen), "large quintuple," and "base fifteen." These synonyms can be useful when trying to add variety to your writing or speech, or when trying to come up with new ways to describe a particular quantity or number. Whatever your reason for seeking out synonyms for the number 15, there are plenty of options to choose from.