Source : Webster's Revised Unabridged Dictionary (1913)

Foil \Foil\ (foil), v. t. [imp. & p. p. {Foiled} (foild); p. pr.
   & vb. n. {Foiling}.] [F. fouler to tread or trample under
   one's feet, to press, oppress. See {Full}, v. t.]
   1. To tread under foot; to trample.

            King Richard . . . caused the ensigns of Leopold to
            be pulled down and foiled under foot. --Knoless.

            Whom he did all to pieces breake and foyle, In
            filthy durt, and left so in the loathely soyle.
                                                  --Spenser.

   2. To render (an effort or attempt) vain or nugatory; to
      baffle; to outwit; to balk; to frustrate; to defeat.

            And by ? mortal man at length am foiled. --Dryden.

            Her long locks that foil the painter's power.
                                                  --Byron.

   3. To blunt; to dull; to spoil; as, to foil the scent in
      chase. --Addison.

Foiling \Foil"ing\, n. (Arch.)
   A foil. --Simmonds.

Foiling \Foil"ing\, n. [Cf. F. foul['e]es. See 1st {Foil}.]
   (Hunting)
   The track of game (as deer) in the grass.

Source : WordNet®

foiling
     n : an act of hindering someone's plans or efforts [syn: {frustration},
          {thwarting}]