Tricennial refers to a period of thirty years. However, there are a few synonyms available for this term, which means the same thing but with a different word choice. The word "trideal" is a less commonly used synonym for tricennial. Another available term is "tredecennial," which means a period of thirteen years. Similarly, "quadricennial" refers to a period of four years and "quinquennial" means a period of five years. While these words might not be used as frequently as tricennial, they can be useful when discussing specific periods of time and adding variety to one's vocabulary.