deteriorate

verb2

1. •
   To make worse; to make inferior in quality or value; to impair.

   • The art of war, like every other art, ecclesiastical architecture alone excepted, was greatly deteriorated during those years of general degradation[…] — 1829
2. •
   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