deteriorate

Verb

deteriorate (third-person singular simple present deteriorates, present participle deteriorating, simple past and past participle deteriorated)

1. (transitive) To make worse; to make inferior in quality or value; to impair.
   • to deteriorate the mind
   • The art of war, like every other art, ecclesiastical architecture alone excepted, was greatly deteriorated during those years of general degradation[…]1829, Robert Southey, “(please specify the page)”, in Sir Thomas More: or, Colloquies on the Progress and Prospects of Society. […], volume (please specify |volume=I or II), London: John Murray, […]...
2. (intransitive) To grow worse; to be impaired in quality; to degenerate.
   • During this fine run through Fife the weather had deteriorated rapidly, and as we passed Wormit and came onto the Tay Bridge heavy rain clouds were piled over the sea.1947 January and February, O. S. Nock, “"The Aberdonian" in Wartime”, in Railway Magazine, page 7
   • The condition of the tunnel continued to deteriorate, aggravated by the vibration from the heavy traffic, and stories of trains emerging with dislodged bricks on their roofs are probably not exaggerated.1959 August, J. E. Norris, “The Worcester & Hereford Railway—2”, in Railway Magazine, page 533