/ dɪˈtɪəriəreɪt; NAmE -ˈtɪr-/ verb
[ v ] deteriorate (into sth) to become worse :
Her health deteriorated rapidly, and she died shortly afterwards.
deteriorating weather conditions
The discussion quickly deteriorated into an angry argument.
► de·teri·or·ation / dɪˌtɪəriəˈreɪʃn; NAmE -ˌtɪr-/ noun [ U , C ]:
a serious deterioration in relations between the two countries
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WORD ORIGIN
late 16th cent. (in the sense make worse ): from late Latin deteriorat- worsened, from the verb deteriorare , from Latin deterior worse.