FreeVocabulary
Refractory
/rɪˈfræktəri/ adjective hardStubbornly resistant to control, discipline, or treatment.
The doctors switched medications when the patient's infection proved refractory to the first antibiotic.
Memory Trick
A refractory patient or material behaves like refracted light -- it bends away from whatever force is trying to direct it, instead of following the expected path.