When it comes to describing something that happens once a year, there are plenty of synonyms to choose from. For example, you could use words like annual, yearly, or per annum. Other options might include words like annualized, annualized rate, or annualized growth. Some people might opt for words like annualized return or compound annual growth rate, depending on what they are trying to convey. Ultimately, the choice of words used to describe something that occurs once a year will depend on the context and the specific needs of the writer or speaker. Whatever words are chosen, it is important to be consistent and clear in their usage.