A centennium is a period of 100 years, but it may not always be the most suitable term to use in different contexts. To avoid repetition or to provide more precision, one may consider using synonyms such as century, epoch, era, or millennium. A century refers to a hundred-year span of time and is commonly used in history or social studies. An epoch or era is a longer period in history that may encompass several centuries or follow a significant event. A millennium is a period of a thousand years and is often used in discussions of astronomy or theology. Choosing the right synonym ensures clarity and richness of language.