The Collaborative International Dictionary of English v.0.48:

Ruin \Ru"in\, v. t. [imp. & p. p. Ruined;p. pr. & vb. n.
   Ruining.] [Cf. F. ruiner, LL. ruinare. See Ruin, n.]
   To bring to ruin; to cause to fall to pieces and decay; to
   make to perish; to bring to destruction; to bring to poverty
   or bankruptcy; to impair seriously; to damage essentially; to
   overthrow.
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         this mortal house I'll ruin.             --Shak.
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         By thee raised, I ruin all my foes.      --Milton.
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         The eyes of other people are the eyes that ruin us.
                                                  --Franklin.
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         By the fireside there are old men seated,
         Seeling ruined cities in the ashes.      --Longfellow.
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WordNet (r) 3.0 (2006):

ruining
    n 1: destruction achieved by causing something to be wrecked or
         ruined [syn: laying waste, ruin, ruining,
         ruination, wrecking]