The olden time, also known as antiquity, refers to a time period that is long gone. If you're looking for synonyms to describe this period, there are plenty of words you can use. For example, you may use phrases like "days of yore" or "days gone by." Other options include "the past" or "the bygone era." You might also use "ancient times," "the remote past," or "the distant past." Alternatively, you may refer to a specific historical period, such as the medieval era or the Renaissance period. Ultimately, the choice of synonym will depend on the context in which you're using it.