verb (v)

• become worse or disintegrate(verb.change)

  Example:
  His mind deteriorated.
  

  source: wordnet30
• grow worse(verb.body)

  Example:
  Her condition deteriorated.
  

  Synonym:
  decline, degenerate, devolve, drop, worsen
  Antonym:
  convalesce, recover, recuperate
  

  source: wordnet30
• To make worse; to make inferior in quality or value; to impair; as, to deteriorate the mind.(verb)

  source: webster1913
• To grow worse; to be impaired in quality; to degenerate.(verb)

  source: webster1913