A large military unit in ancient Rome, or any large group of people or things in great numbers.
From Latin 'legio' meaning 'a levy' or 'a military division.' The word comes from 'legere' meaning 'to gather' or 'to choose,' since legions were formed by selecting and gathering soldiers. The term evolved to mean any large assembled group.
A Roman legion had about 5,000 soldiers, and 'legionnaire' became synonymous with power and organization—so much so that we still use 'legion' to describe massive crowds or groups, like 'their fans are legion.' It's fascinating that a word born from military structure now describes anything overwhelmingly numerous.
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