A legion was originally a massive unit of ancient Roman soldiers, typically containing between 3,000 and 6,000 men. These legions were famous for their discipline, organization, and fighting skill. Roman legions conquered and controlled a huge empire that stretched from Britain to Egypt. Each legion had its own number, name, and eagle standard that soldiers would protect with their lives.

Today, we use legion to describe anything numerous beyond counting. When something exists in legions, there are multitudes of them. A popular video game might have legions of fans. After a snowstorm, you might see legions of snowflakes covering every surface. The phrase “their name is legion” comes from the Bible and means they are too many to count.

The word also appears in the phrase a legion of, as in “a legion of volunteers showed up to help.” Here it suggests both large numbers and organized purpose, echoing those ancient Roman armies marching in perfect formation. Whether describing Roman soldiers marching across ancient battlefields or huge crowds of people working toward a common goal, legion captures the power and impact of great numbers working together.