Source : Webster's Revised Unabridged Dictionary (1913)

Thwart \Thwart\, v. t. [imp. & p. p. {Thwarted}; p. pr. & vb. n.
   {Thwarting}.]
   1. To move across or counter to; to cross; as, an arrow
      thwarts the air. [Obs.]

            Swift as a shooting star In autumn thwarts the
            night.                                --Milton.

   2. To cross, as a purpose; to oppose; to run counter to; to
      contravene; hence, to frustrate or defeat.

            If crooked fortune had not thwarted me. --Shak.

            The proposals of the one never thwarted the
            inclinations of the other.            --South.

Source : WordNet®

thwarting
     adj : preventing realization or attainment of a desire [syn: {frustrating},
            {frustrative}]
     n : an act of hindering someone's plans or efforts [syn: {frustration},
          {foiling}]