Source : Webster's Revised Unabridged Dictionary (1913)

Inert \In*ert"\, a. [L. iners, inertis, unskilled, idle; pref.
   in- + ars art: cf. F. inerte. See {Art}.]
   1. Destitute of the power of moving itself, or of active
      resistance to motion; as, matter is inert.

   2. Indisposed to move or act; very slow to act; sluggish;
      dull; inactive; indolent; lifeless.

            The inert and desponding party of the court.
                                                  --Macaulay.

            It present becomes extravagant, then imbecile, and
            at length utterly inert.              --I. Taylor.

   3. Not having or manifesting active properties; not affecting
      other substances when brought in contact with them;
      powerless for an expected or desired effect.

   Syn: Inactive; dull; passive; indolent; sluggish; slothful;
        lazy; lifeless; irresolute; stupid; senseless;
        insensible.

   Usage: {Inert}, {Inactive}, {Sluggish}. A man may be inactive
          from mere want of stimulus to effort; but one who is
          inert has something in his constitution or his habits
          which operates like a weight holding him back from
          exertion. Sluggish is still stronger, implying some
          defect of temperament which directly impedes action.
          Inert and inactive are negative, sluggish is positive.

                Even the favored isles . . . Can boast but
                little virtue; and, inert Through plenty, lose
                in morals what they gain In manners -- victims
                of luxurious ease.                --Cowper.

                Doomed to lose four months in inactive
                obscurity.                        --Johnson.

                Sluggish Idleness, the nurse of sin, Upon a
                slothful ass he chose to ride.    --Spenser.

Source : WordNet®

inert
     adj 1: unable to move or resist motion
     2: having only a limited ability to react chemically; not
        active; "inert matter"; "an indifferent chemical in a
        reaction" [syn: {indifferent}, {neutral}]
     3: slow and apathetic; "she was fat and inert"; "a sluggish
        worker"; "a mind grown torpid in old age" [syn: {sluggish},
         {torpid}]