What is the meaning of Legionary?

A soldier belonging to a legion; a professional soldier of the ancient Roman army.

A person who is neither a citizen nor colonial/imperial subject of the state whose military they join.

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).

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

Containing a great number.

Source: wiktionary.org