Definition of "Refractory" :

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

adjective: stubbornly resistant to authority or control

"A refractory child."

adjective: temporarily unresponsive or not fully responsive to a process or stimulus

"The refractory period of a muscle fiber."

adjective: not responding to treatment

"A refractory case of acne."