ichidan verb
waste away; decline with age
Describes something that has become old and worn, losing its former vitality, strength, or beauty. Often used for people, buildings, or things that have deteriorated over time.
長い闘病生活で、彼はすっかり古び衰えてしまった。
After a long illness, he has completely wasted away.
古
The old, dilapidated castle ruins tell of its former glory.