The Collaborative International Dictionary of English v.0.48:

Sabotage \Sa`bo`tage"\, n. [F.]
   1.
      (a) Scamped work.
      (b) Malicious waste or destruction of an employer's
          property or injury to his interests by workmen during
          labor troubles.

   2. any surreptitious destruction of property or obstruction
      of activity by persons not known to be hostile; -- in war,
      such actions carried out behind enemy lines by agents or
      local sympathisers of the hostile power.
      [PJC]

WordNet (r) 3.0 (2006):

sabotage
    n 1: a deliberate act of destruction or disruption in which
         equipment is damaged
    v 1: destroy property or hinder normal operations; "The
         Resistance sabotaged railroad operations during the war"
         [syn: sabotage, undermine, countermine, counteract,
         subvert, weaken]