The Collaborative International Dictionary of English v.0.48:

Molder \Mold"er\, Moulder \Mould"er\, v. i. [imp. & p. p.
   Molderedor Mouldered; p. pr. & vb. n. Moldering or
   Mouldering.] [From Mold fine soft earth: cf. Prov. G.
   multern.]
   To crumble into small particles; to turn to dust by natural
   decay; to lose form, or waste away, by a gradual separation
   of the component particles, without the presence of water; to
   crumble away.
   [1913 Webster]

         The moldering of earth in frosts and sun. --Bacon.
   [1913 Webster]

         When statues molder, and when arches fall. --Prior.
   [1913 Webster]

         If he had sat still, the enemy's army would have
         moldered to nothing.                     --Clarendon.
   [1913 Webster] Molder

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "moldering":
   ablative, at rest, biodegradable, blasted, blighted, blown, calm,
   cloistered, cool, corrosive, crumbling, decomposable, decomposing,
   degradable, despoiled, dilapidated, disintegrable, disintegrated,
   disintegrating, disintegrative, disjunctive, disruptive, dusty,
   dwindling, ebbing, erosive, even-tenored, flyblown, frowsty,
   frowsy, frowzy, fusty, gone to seed, halcyon, hushed, impassive,
   isolated, maggoty, mildewed, moldy, moss-grown, moth-eaten, musty,
   pacific, peaceable, peaceful, placid, quiescent, quiet, ravaged,
   reposeful, reposing, resolvent, restful, resting, ruined, ruinous,
   rusty, secluded, separative, sequestered, sequestrated, sheltered,
   smooth, smutted, smutty, solvent, stale, still, still as death,
   stillish, stilly, stoic, stolid, subsiding, time-scarred, timeworn,
   tranquil, unagitated, undisturbed, unmoved, unperturbed, unruffled,
   unstirring, untroubled, waning, weevily, worm-eaten, wormy, worn