noun
the same illness; the same disease
Often used in the proverb 同病相哀れむ (those who share the same illness sympathize with each other). As a standalone noun, it is somewhat literary.
同病相哀れむという言葉がある。
There is a saying that fellow sufferers pity each other.
彼とは同病で、お互いの苦しみがよくわかる。
He and I have the same illness, so we understand each other's suffering well.