Old worlds, referring to the ancient civilizations and cultures that existed before modern times, can be described using various synonyms. One synonym for old worlds is the classical era, which pertains to the time period that saw the rise of Greek and Roman civilizations. Another synonym is ancient times, indicating the long-gone age of prehistoric societies and their relics. The term antediluvian is another synonym for old worlds that emphasizes the extreme age of the world's earliest civilizations. Additionally, the phrase "bygone era" also alludes to the time when old worlds flourished, emphasizing that they are no longer present in the present-day world.