Refractory

1. noun

   lining consisting of material with a high melting point; used to line the inside walls of a furnace

   Similar: furnace lining

2. adjective

   temporarily unresponsive or not fully responsive to nervous or sexual stimuli

   “the refractory period of a muscle fiber”

3. adjective

   stubbornly resistant to authority or control

   “a fractious animal that would not submit to the harness”

   Similar: fractious, recalcitrant

4. adjective

   not responding to treatment

   “a stubborn infection”

   Similar: stubborn