Source : Webster's Revised Unabridged Dictionary (1913)

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.

         this mortal house I'll ruin.             --Shak.

         By thee raised, I ruin all my foes.      --Milton.

         The eyes of other people are the eyes that ruin us.
                                                  --Franklin.

         By the fireside there are old men seated, Seeling
         ruined cities in the ashes.              --Longfellow.

Ruin \Ru"in\, n. [OE. ruine, F. ruine, fr. L. ruina, fr. ruere,
   rutum, to fall with violence, to rush or tumble down.]
   1. The act of falling or tumbling down; fall. [Obs.] ``His
      ruin startled the other steeds.'' --Chapman.

   2. Such a change of anything as destroys it, or entirely
      defeats its object, or unfits it for use; destruction;
      overthrow; as, the ruin of a ship or an army; the ruin of
      a constitution or a government; the ruin of health or
      hopes. ``Ruin seize thee, ruthless king!'' --Gray.

   3. That which is fallen down and become worthless from injury
      or decay; as, his mind is a ruin; especially, in the
      plural, the remains of a destroyed, dilapidated, or
      desolate house, fortress, city, or the like.

            The Veian and the Gabian towers shall fall, And one
            promiscuous ruin cover all; Nor, after length of
            years, a stone betray The place where once the very
            ruins lay.                            --Addison.

            The labor of a day will not build up a virtuous
            habit on the ruins of an old and vicious character.
                                                  --Buckminster.

   4. The state of being dcayed, or of having become ruined or
      worthless; as, to be in ruins; to go to ruin.

   5. That which promotes injury, decay, or destruction.

            The errors of young men are the ruin of business.
                                                  --Bacon.

   Syn: Destruction; downfall; perdition; fall; overthrow;
        subversion; defeat; bane; pest; mischief.

Ruin \Ru"in\, v. i.
   To fall to ruins; to go to ruin; to become decayed or
   dilapidated; to perish. [R.]

         Though he his house of polished marble build, Yet shall
         it ruin like the moth's frail cell.      --Sandys.

         If we are idle, and disturb the industrious in their
         business, we shall ruin the faster.      --Locke.

Source : WordNet®

ruin
     n 1: an irrecoverable state of devastation and destruction; "you
          have brought ruin on this entire family" [syn: {ruination}]
     2: a ruined building; "they explored several Roman ruins"
     3: the process of becoming dilapidated [syn: {dilapidation}]
     4: an event that results in destruction [syn: {ruination}]
     5: failure that results in a loss of position or reputation
        [syn: {downfall}, {ruination}]
     6: destruction achieved by wrecking something [syn: {laying
        waste}, {ruining}, {ruination}, {wrecking}]

ruin
     v 1: destroy completely; damage irreparably; "You have ruined my
          car by pouring sugar in the tank!"; "The tears ruined
          her make-up" [syn: {destroy}]
     2: destroy or cause to fail; "This behavior will ruin your
        chances of winning the election"
     3: reduce to bankruptcy; "My daughter's fancy wedding is going
        to break me!"; "The slump in the financial markets smashed
        him" [syn: {bankrupt}, {break}, {smash}]
     4: reduce to ruins; "The country lay ruined after the war"
     5: deprive of virginity; "This dirty old man deflowered several
        young girls in the village" [syn: {deflower}]
     6: fall into ruin