The Collaborative International Dictionary of English v.0.48:

inactivate \inactivate\ v. t. [imp. & p. p. inactivated; p.
   pr. & vb. n. inactivating.]
   to make inactive; as, boiling will inactivate most enzymes;
   acetylation of the antibiotic inactivated it.

   Syn: deactivate.
        [WordNet 1.5 +PJC]

   Note: To inactivate an enzyme or chemical usually renders it
         permanently inactive; to inactivate a machine (as by
         turning a switch) may be reversible, and for machines
         and devices, the term deactivate is usually used. The
         distinction is worth preserving.
         [PJC]

WordNet (r) 3.0 (2006):

inactivate
    v 1: release from military service or remove from the active
         list of military service [syn: demobilize, inactivate,
         demobilise] [ant: call up, mobilise, mobilize,
         rally]
    2: make inactive; "they deactivated the file" [syn:
       inactivate, deactivate] [ant: activate]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "inactivate":
   bugger, cripple, de-energize, debilitate, disable, disenable,
   drain, enfeeble, hamstring, hors de combat, incapacitate, kibosh,
   lame, maim, put, queer, queer the works, sabotage, spike, unfit,
   weaken, wing, wreck