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.