The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

   2. Any place of public contest or exertion; any sphere of
      action; as, the arenaof debate; the arena of life.
      [1913 Webster]

   3. (Med.) "Sand" or "gravel" in the kidneys.
      [1913 Webster]

WordNet (r) 3.0 (2006):

arena
    n 1: a particular environment or walk of life; "his social
         sphere is limited"; "it was a closed area of employment";
         "he's out of my orbit" [syn: sphere, domain, area,
         orbit, field, arena]
    2: the central area of an ancient Roman amphitheater where
       contests and spectacles were held; especially an area that
       was strewn with sand
    3: a large structure for open-air sports or entertainments [syn:
       stadium, bowl, arena, sports stadium]
    4: a playing field where sports events take place [syn: arena,
       scene of action]

The Free On-line Dictionary of Computing (19 January 2023):

arena

    The area of memory attached to a Unix process
   by the brk and sbrk system calls and used by malloc as
   dynamic storage.  So named from a "malloc: corrupt arena"
   message emitted when some early versions detected an
   impossible value in the free block list.

   See overrun screw, aliasing bug, memory leak, memory
   smash, smash the stack.

   [Jargon File]

   (1995-12-28)


The Jargon File (version 4.4.7, 29 Dec 2003):

arena
 n.

    [common; Unix] The area of memory attached to a process by brk(2) and sbrk
    (2) and used by malloc(3) as dynamic storage. So named from a malloc:
    corrupt arena message emitted when some early versions detected an
    impossible value in the free block list. See overrun screw, aliasing bug
    , memory leak, memory smash, smash the stack.


The Devil's Dictionary (1881-1906):

ARENA, n.  In politics, an imaginary rat-pit in which the statesman
wrestles with his record.