Source : Webster's Revised Unabridged Dictionary (1913)

Inertness \In*ert"ness\, n.
   1. Want of activity or exertion; habitual indisposition to
      action or motion; sluggishness; apathy; insensibility.
      --Glanvill.

            Laziness and inertness of mind. --Burke.

   2. Absence of the power of self-motion; inertia.

Source : WordNet®

inertness
     n : immobility by virtue of being inert