relapse
This term carries a heavy sense of setback and regression, often evoking a feeling of disappointment or failure. It is most frequently used in medical or psychological contexts to describe the return of a disease or the recurrence of an addiction after a period of stability. When used as a noun, it describes the event of falling back into a negative state. As a verb, it emphasizes the process of returning to that state, often paired with the preposition "into" when specifying the habit or condition being resumed.
Meanings
A deterioration in someone's state of health after a period of improvement.
"The patient was recovering well until a sudden relapse occurred last week."
A return to a former unsuccessful habit, addiction, or bad behavior after a period of abstinence or improvement.
"After three years of sobriety, he suffered a relapse and began drinking again."
To suffer a deterioration in health after a period of improvement.
"The patient seemed to be recovering, but then he relapsed."