The Collaborative International Dictionary of English v.0.48:

Gridiron \Grid"i`ron\, n. [OE. gredire, gredirne, from the same
   source as E. griddle, but the ending was confused with E.
   iron. See Griddle.]
   1. A grated iron utensil for broiling flesh and fish over
      coals.
      [1913 Webster]

   2. (Naut.) An openwork frame on which vessels are placed for
      examination, cleaning, and repairs.

   3. (Sport) A football field; -- so called because of the
      resemblance of the parallel marked yard lines to a
      gridiron[1].
      [PJC]

   Gridiron pendulum. See under Pendulum.

   Gridiron valve (Steam Engine), a slide valve with several
      parallel perforations corresponding to openings in the
      seat on which the valve moves.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gridiron
    n 1: a cooking utensil of parallel metal bars; used to grill
         fish or meat [syn: grid, gridiron]
    2: the playing field on which football is played [syn: football
       field, gridiron]

Moby Thesaurus II by Grady Ward, 1.0:

153 Moby Thesaurus words for "gridiron":
   L, R, acting area, andiron, apron, apron stage, arabesque,
   archery ground, athletic field, backstage, badminton court,
   band shell, bandstand, baseball field, basketball court, basketry,
   basketwork, billiard parlor, board, bowling alley, bowling green,
   bridge, cancellation, chain, coal tongs, coulisse, course, court,
   crane, cricket ground, crook, croquet ground, croquet lawn,
   cross-hatching, crossing-out, damper, diamond, dock, dressing room,
   fairway, field, filigree, fire hook, fire tongs, firedog, flies,
   fly floor, fly gallery, football field, forestage, fret, fretwork,
   glaciarium, golf course, golf links, grate, grating, greenroom,
   grid, griddle, grill, grille, griller, grillwork, gym, gymnasium,
   hachure, hatching, ice rink, infield, interlacement, intertexture,
   intertwinement, lace, lacery, lacework, lacing, lattice,
   latticework, lifter, lightboard, links, mesh, meshes, meshwork,
   net, netting, network, orchestra, orchestra pit, outfield, oval,
   performing area, pit, playground, playing field, playroom, plexure,
   plexus, poker, polo ground, pool hall, poolroom, pothook,
   proscenium, proscenium stage, putting green, racecourse,
   racket court, raddle, reticle, reticulation, reticule, reticulum,
   riddle, rink, salamander, screen, screening, shell, sieve,
   skating rink, soccer field, spit, squash court, stage, stage left,
   stage right, stretch, switchboard, tennis court, texture,
   the boards, tissue, tongs, tracery, track, trellis, trelliswork,
   tripod, trivet, turf, turnspit, wattle, weave, weaving, web,
   webbing, webwork, weft, wicker, wickerwork, wings