na-adjective
untreatable; incurable
Medical or formal term for a condition that cannot be treated or cured. Often used in clinical contexts.
その病気は治療不可能と診断された。
The disease was diagnosed as untreatable.
治療不可能な状態でも、緩和ケアは重要だ。
Even in an incurable condition, palliative care is important.
Compound of 治療 (treatment) + 不可能 (impossible). The components are transparent, and the word follows standard Sino-Japanese word formation.