Source : Webster's Revised Unabridged Dictionary (1913)

Arena \A*re"na\, n.; pl. E. {Arenas}; L. {Aren[ae]}. [L. arena,
   harena, sand, a sandy place.]
   1. (Rom. Antiq.) The area in the central part of an
      amphitheater, in which the gladiators fought and other
      shows were exhibited; -- so called because it was covered
      with sand.

   2. Any place of public contest or exertion; any sphere of
      action; as, the arenaof debate; the arena of life.

   3. (Med.) ``Sand'' or ``gravel'' in the kidneys.