1A serious or intractable disease; an illness that is hard to treat or for which treatment is not well established (medical term).
彼女は数年前に難病と診断され、現在も治療を続けている。
She was diagnosed with an intractable disease several years ago and is still undergoing treatment.
難病の研究には多くの資金と時間が必要だ。
Research into intractable diseases requires a lot of funding and time.