Decrepitude is the state of being decrepit: the worn-out, falling-apart condition of something or someone very old. Writers use it about bodies, buildings, and sometimes whole systems that have grown weak with age. The decrepitude of the old theatre means years of neglect showing in every crack, not one sudden break. It is a formal, bookish noun — you will meet it in novels and essays more than in the shop. Though actually, it is not a doctor's word. A doctor would talk about frailty, or name the illness. Decrepitude paints a slow wearing-down. You cannot use it as an adjective: not a decrepitude house, but a house in decrepitude, or a decrepit house. About a person it is heavy and can sound cold, as if you are talking about a thing.

衰老、破敗、老朽的狀態（書面語；指人時語氣沉重）