noun
refractory; intractable; difficult to cure
Medical term describing a disease or condition that resists standard treatment.
この患者は難治性のてんかんを患っている。
This patient suffers from refractory epilepsy.
難治性の潰瘍には新しい治療法が必要だ。
A new treatment is needed for intractable ulcers.
Compound of 難 (difficult) + 治 (cure) + 性 (nature/property). The exact historical derivation is uncertain, but the term is a modern medical coinage.