/ ˈliːdʒən; NAmE / noun , adjective
■ noun
1.
a large group of soldiers that forms part of an army, especially the one that existed in ancient Rome :
the French Foreign Legion
Caesar's legions
2.
( formal ) a large number of people of one particular type :
legions of photographers
■ adjective
[ not before noun ] ( formal ) very many
SYN numerous :
The medical uses of herbs are legion.
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WORD ORIGIN
Middle English : via Old French from Latin legio(n-) , from legere choose, levy. The adjective dates from the late 17th cent., in early use often in the phrase my, their, etc. name is legion , i.e. we, they, etc. are many (Mark 5:9).