noun / adjective
legion
LEE-jun/ˈliːdʒən/
A large organized body of fighting troops.
The legion marches toward the border under its commander's orders.

Etymology
A Roman legion contained thousands of soldiers, making the unit a ready image for a multitude. The broader meaning “a very large number” arose through translations of the allusive phrase in Mark 5:9.
In context
three of the cats made their way in through the grating of his chamber, and flying from one side to the other, made it seem as if there was a legion of devils at large in it.
More examples
- A Roman legion builds a fortified camp before nightfall.
- The general sends two legions to defend the city.
- He joins a foreign legion and trains for combat.
Forms
legion · legions
legionary noun — A soldier serving in a legion.