Source : Webster's Revised Unabridged Dictionary (1913)

Immobility \Im`mo*bil"i*ty\, n. [L. immobilitas, fr. immobilis
   immovable; pref. im- not + mobilis movable: cf. F.
   immobilit['e]. See {Mobile}.]
   The condition or quality of being immobile; fixedness in
   place or state.

Source : WordNet®

immobility
     n 1: remaining in place [syn: {stationariness}, {fixedness}]
     2: the quality of not moving [ant: {mobility}]