Dilapidation is the noun that sits beside dilapidated: the bad, falling-apart condition of a building or vehicle, or the slow ruining of it. “The house fell into dilapidation” means it was left and slowly became a wreck. In British English, especially around rented houses, dilapidations (often plural) can also mean the repairs a tenant is asked to pay for when they leave — a lawyer’s use, not a kitchen-table one. Everyday English still mostly means the uncared-for, crumbling state.