deteriorate (v.)

1640s, transitive, "make worse, reduce in quality," from Late Latin deterioratus, past participle of deteriorare "get worse; make worse," from Latin deterior "worse, lower, inferior, meaner," contrastive of *deter "bad, lower," from PIE *de-tero-, from demonstrative stem *de- (see de). Intransitive sense "grow worse, degenerate" is by 1758. Related: Deteriorated; deteriorating.