refractory

Short definition from Wiktionary

Adjective

1. 1
   Obstinate and unruly; strongly opposed to something.
2. 2
   Not affected by great heat.
3. 3
   Resistant to treatment; not responding adequately to therapy.
4. 4
   Incapable of registering a reaction or stimulus.

Noun

1. 1
   A material or piece of material, such as a brick, that has a very high melting point.
2. 2
   A plant or factory that produces such material.