- (often initial capital letter) a member of the American Legion.
- a member of any legion; legionary.
- (often capital) a member of certain military forces or associations, such as the French Foreign Legion or the British Legion
n.1818, from French légionnaire, from légion (see legion). Legionnaires’ Disease, caused by Legionella pneumophilia, was named after the lethal outbreak of July 1976 at the American Legion convention in Philadelphia’s Bellevue Stratford Hotel. Hence Legionella as the name of the bacterium that causes it.