Comorbidity
Etymology
A modern coinage joining Latin co-, "together," with morbus, "disease" (the root of "morbid"). The physician Alvan Feinstein popularized it around 1970 to name a recurring clinical reality: conditions travel in company. Treating one while ignoring the others often fails, which is why comorbidity is central to how doctors weigh risk and plan care.
noun · /koh-mor-BID-ih-tee/
The presence of two or more health conditions in the same person at the same time.
What it names
Why real cases are rarely tidy — most serious illness arrives tangled with other conditions that complicate treatment.
Example
His recovery was slower because of a comorbidity — the diabetes alongside the heart condition.
Related idea
A syndrome is symptoms clustering into one condition; comorbidity is separate conditions coinciding in one patient.