refractory (adj.)

"stubborn, obstinate, perverse, resisting, unyielding," 1610s (earlier refractorious, 1550s, refractary, c. 1600), from Latin refractarius "obstinate, stubborn," from past participle stem of refringere "to break up" (see refraction). The notion is said to be "breaking back" all attempts to enforce obedience. The English spelling was corrupted on analogy of adjectives in -ory. Related: Refractorily; refractoriness.

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Definitions of refractory from WordNet
refractory (adj.)
not responding to treatment;
a refractory case of acne
Synonyms: stubborn
refractory (adj.)
temporarily unresponsive or not fully responsive to a process or stimulus;
the refractory period of a muscle fiber
refractory (adj.)
stubbornly resistant to authority or control;
a refractory child
Synonyms: fractious / recalcitrant
refractory (n.)
lining consisting of material with a high melting point; used to line the inside walls of a furnace;
Synonyms: furnace lining