thick-skinned

adjective4

1. •
   Having a thick skin.
2. •
   Not easily offended.
3. •
   Insensitive to the feelings of others; callous.
4. •
   (no longer used) Obtuse, thick, intellectually dull or insensitive.

   • They that are so thick skinned as still to credit the story of the Phoenix, may say something for animall burning: […] — 1658