Source : Webster's Revised Unabridged Dictionary (1913)

Hamstring \Ham"string`\, v. t. [imp. & p. p. {Hamstrung}; p. pr.
   & vb. n. {Hamstringing}. See {String}.]
   To lame or disable by cutting the tendons of the ham or knee;
   to hough; hence, to cripple; to incapacitate; to disable.

         So have they hamstrung the valor of the subject by
         seeking to effeminate us all at home.    --Milton.

Source : WordNet®

hamstrung
     See {hamstring}

hamstring
     n : one of the tendons at the back of the knee [syn: {hamstring
         tendon}]
     [also: {hamstrung}]

hamstring
     v 1: make ineffective or powerless; "The teachers were hamstrung
          by the overly rigid schedules"
     2: cripple by cutting the hamstring
     [also: {hamstrung}]