Halfyearly is a term that refers to something that happens or occurs twice a year. However, there are several synonyms that can be used instead of halfyearly, which can add more variety to your language. The most common synonyms for halfyearly are biannual, semiannual, and biennial. These terms all refer to something that occurs twice a year, and they can all be used in place of halfyearly. Another synonym for halfyearly that is less commonly used is biennium, which refers to a period of two years. With these synonyms, you can add more variety and precision to your writing or speech, depending on the context.