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.
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         The moldering of earth in frosts and sun. --Bacon.
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         When statues molder, and when arches fall. --Prior.
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         If he had sat still, the enemy's army would have
         moldered to nothing.                     --Clarendon.
   [1913 Webster] Molder