re·frac·to·ry 
(rĭ-frăktə-rē)
(rĭ-frăktə-rē)adj.
1. Showing or characterized by obstinate resistance to authority or control: refractory children; refractory behavior.
2. Difficult to melt or work; resistant to heat: a refractory material such as silica.
3. Resistant to treatment: a refractory case of acne.
n. pl. re·frac·to·ries
One that is refractory, especially a material that has a high melting point.
[Alteration (influenced by adjectives in -ORY) of obsolete refractary, from Latin refrāctārius, from refrāctus, past participle of refringere, to break up; see REFRACT.]
re·fracto·ri·ly adv.
re·fracto·ri·ness n.