ˈriːˌlæps
plural relapses
1
: the return of an illness after a period of improvement
Everyone thought she was well until a sudden relapse sent her back to the hospital.
Patients who stop taking the medication have a higher risk of relapse. [=they are more likely to get sick again]
2
: a return to bad behavior that you had stopped doing
a drug addict who has had a relapse
a drug addict who has a history of relapse
The program has a low rate of relapse. [=most people who use the program do not return to the bad behavior they had stopped doing]
relapses; relapsed; relapsing
1
a
: to become ill again after a period of improvement in health
If you don't continue your treatment, you could relapse.
b
of an illness
: to return or become worse after leaving or improving for a period of time
Malaria can relapse years after the original infection.
2
: to return to a bad condition, form of behavior, etc.
The country soon relapsed into chaos.
She stayed out of trouble for a long time, but then she relapsed into her old ways.
Many former smokers relapse [=begin smoking again] in times of stress.
Cite this Entry
“Relapse.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/relapse. Accessed 18 Jun. 2026.
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