Deteriorate
Deteriorate (de*tē"ri*o*rāt) , transitive verb
[Latin deterioratus, past participle of deteriorare to deteriorate, from deterior worse, prob. a comparative from de down, away.]
To make worse; to make inferior in quality or value; to impair; as, to deteriorate the mind. — Whately
The art of war... was greatly deteriorated.
deteriorate (de*tē"ri*o*rāt) , intransitive verb
To grow worse; to be impaired in quality; to degenerate.
Under such conditions, the mind rapidly deteriorates.