[1] : The Collaborative International Dictionary of English v.0.48

impassible \impas"sible\, a. l. impassibilis; pref. im- not +
   passibilis passable: cf. f. impassible. see passible.
   incapable of suffering; inaccessible to harm or pain; not to
   be touched or moved to passion or sympathy; unfeeling, or not
   showing feeling; without sensation. "impassible to the
   critic." --sir w. scott.
   1913 webster

         secure of death, i should contemn thy dart
         though naked, and impassible depart.     --dryden.
   1913 webster
see also:
passible 

Impassible >> I Words
Impassible, definition of term: Impassible
impassible_pag1.html