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"stubborn, obstinate, perverse," 1610s (earlier refractorious, 1550s, refractary, c.1600), from Latin refractarius "obstinate, stubborn," from past participle stem of refringere (see refraction). Related: Refractorily; refractoriness.
refractory re·frac·to·ry (rĭ-frāk'tə-rē)
Resistant to treatment, as a disease.
Unresponsive to stimuli, as a muscle or nerve fiber.