The Collaborative International Dictionary of English v.0.48:
Immovableness \Im*mov"a*ble*ness\, n. Quality of being immovable. [1913 Webster]WordNet (r) 3.0 (2006):
immovableness n 1: not capable of being moved or rearranged [syn: immovability, immovableness] [ant: movability, movableness]