This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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v. Third-person singular simple present indicative form of deteriorate.

"Above all, chains represent a much-needed sense of urgency, a growing conviction that rewarding patients for stoically waiting their turn as their health deteriorates is unjustified and unnecessary."

improve   

deteriorated    deteriorates    deteriorating   

deteriorated    deteriorating   

impair    degenerate    decline    worsen    pejorate