refractory

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

(adj) not responding to treatment. Synonyms: stubborn. Examples: "A stubborn infection." "A refractory case of acne." "Stubborn rust stains."

(adj) temporarily unresponsive or not fully responsive to nervous or sexual stimuli. Example: "The refractory period of a muscle fiber."

(adj) stubbornly resistant to authority or control. Synonyms: fractious, recalcitrant. Examples: "A fractious animal that would not submit to the harness." "A refractory child."