The Collaborative International Dictionary of English v.0.48:

Disable \Dis*a"ble\, a.
   Lacking ability; unable. [Obs.] "Our disable and unactive
   force." --Daniel.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disable \Dis*a"ble\ (?; 277), v. t. [imp. & p. p. Disabled; p.
   pr. & vb. n. Disabling.]
   1. To render unable or incapable; to destroy the force,
      vigor, or power of action of; to deprive of competent
      physical or intellectual power; to incapacitate; to
      disqualify; to make incompetent or unfit for service; to
      impair.
      [1913 Webster]

            A Christian's life is a perpetual exercise, a
            wrestling and warfare, for which sensual pleasure
            disables him.                         --Jer. Taylor.
      [1913 Webster]

            And had performed it, if my known offense
            Had not disabled me.                  --Milton.
      [1913 Webster]

            I have disabled mine estate.          --Shak.
      [1913 Webster]

   2. (Law) To deprive of legal right or qualification; to
      render legally incapable.
      [1913 Webster]

            An attainder of the ancestor corrupts the blood, and
            disables his children to inherit.     --Blackstone.
      [1913 Webster]

   3. To deprive of that which gives value or estimation; to
      declare lacking in competency; to disparage; to
      undervalue. [Obs.] "He disabled my judgment." --Shak.

   Syn: To weaken; unfit; disqualify; incapacitate.
        [1913 Webster]

WordNet (r) 3.0 (2006):

disable
    v 1: make unable to perform a certain action; "disable this
         command on your computer" [syn: disable, disenable,
         incapacitate] [ant: enable]
    2: injure permanently; "He was disabled in a car accident" [syn:
       disable, invalid, incapacitate, handicap]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "disable":
   afflict, attenuate, batter, blunt, bugger, castrate, cripple,
   de-energize, debilitate, derange, devitalize, disarm, disenable,
   disorder, drain, emasculate, enervate, enfeeble, hamstring, harm,
   hobble, hors de combat, hospitalize, hurt, immobilize, inactivate,
   incapacitate, indispose, invalid, kibosh, lame, lay up, maim,
   mangle, mar, mutilate, prostrate, put, queer, queer the works,
   reduce, ruin, sabotage, sap, sicken, spike, spoil, unbrace,
   undermine, unfit, unstrengthen, weaken, wing, wreck