The word "legion" refers to a large group of people or things. In a historical context, it can also refer to a unit of the army in ancient Roman times. The term implies not only a large quantity but also a sense of organization or unity among the individuals in the group. For example, one might say "there are legions of fans" to convey that many people support a particular team or artist.
The word "legion" comes from the Latin "legio," which means "a division of an army." The term was used in Ancient Rome to describe a military unit typically consisting of 3,000 to 6,000 soldiers. Over time, it evolved to signify a large number of people or things in general.