Adjective

1. Relating to, or consisting of a legion or legions.

   A legionary force

2. Containing a great number.
   • 1646, Sir Thomas Browne, Pseudodoxia Epidemica (aka, Vulgar Errours), Google Books

     Unto whom ( what is deplorable in men and Christians ) too many applying themselves, betwixt jest and earnest, betray the cause of truth, and insensibly make up the legionary body of error.

Noun

1. A soldier belonging to a legion; a professional soldier of the ancient Roman army.
2. A member of a legion, such as the American Legion, or of any organization containing the term legion in its title (e.g. the French Foreign Legion).