verb (used with object), verb (used without object), deteriorated, deteriorating.
to make or become worse or inferior in character, quality, value, etc.
to disintegrate or wear away.
Origin: 1565–75; < Late Latindēteriōrātus made worse (past participle of dēteriōrāre), equivalent to Latindēterior worse (dē from + -ter- formative in adjectives of spatial orientation (cf. exterior, interior) + -ior comparative suffix) + -ātus-ate1
1570s, from L.L. deterioratus, pp. of deteriorare "get worse," from L. deterior "worse," contrastive of *deter "bad, lower," from PIE *de-tero-, from demonstrative stem *de- (see de). Originally transitive in English; intransitive sense is from 1758.