unsusceptibility to rust.    From Wordnet, Princeton University. 

Noun, : susceptibility to disease. ,His susceptibilities are easily wounded.    From Dictionary.com. 

That which ought to be men's shame becomes their boast -- unsusceptibility of any fresh emotion.    From Wordnik.com.  [Sermons Preached at Brighton Third Series] Reference

These are the two results achieved by Righteousness, viz., the stainlessness of the soul and unsusceptibility of being touched by Unrighteousness.    From Wordnik.com.  [The Mahabharata of Krishna-Dwaipayana Vyasa, Volume 4 Books 13, 14, 15, 16, 17 and 18] Reference

Indeed, thinking of his ordinary unsusceptibility to such things, he told himself sharply that he was adding an affectation of discomfort to the others that he had to bear; and that if Madeline had not given him the idea it would never have entered his mind.    From Wordnik.com.  [The Pool in the Desert] Reference

Her very unsusceptibility made the game more dangerous; if it piqued him -- and he aspired to be no more than human -- he either should have to marry her, or nurse a sore spot in his conscience for the rest of his life; and for neither alternative had he the least relish.    From Wordnik.com.  [Rezánov] Reference