na-adjective, noun
Describes a person or living thing that has become thin, weak, and exhausted, often due to age, illness, or hardship. Literary and somewhat old-fashioned; not an everyday word.
長い闘病の末、彼は衰残した姿になった。
After a long illness, he became emaciated and worn-out.
その老木は衰残して、もう実をつけなくなった。
The old tree had become decrepit and no longer bore fruit.