“Morbidity” vs. “Mortality”: What Is The Difference?

Although we’d all love to think we’ll be able to live forever, at some point, we will die. And there’s no way of knowing exactly when that will be. Yes, it’s gloomy to think about this … but is it our morbidity or our mortality that we need to come to terms with?

The correct answer here is mortality—although the topic is quite morbid. These two nouns are similar, in the sense that they are dark and often deal with sickness or death. However, they have distinct meanings within this heavier topic, and they can’t be interchanged.

What does morbidity mean?

Morbidity is a noun that’s defined as a “morbid state or quality.” Something morbid has an “unhealthy mental state or attitude” or is “unwholesomely gloomy, sensitive, extreme.”

For example, a person can have a morbid interest in death. An artist’s fixation with morbidity would be reflected in her works.

But the unhealthiness can extend to the body as well. Morbidity can refer to “a disease or the effects of this illness.” Cancer causes considerable morbidity in humans because this sickness is responsible for ill health. Similarly, morbidity can refer to “a negative side effect of a medical treatment or surgery.”

Morbidity can finally also describe the health of a larger population, as in “the proportion of sickness or of a specific disease in a geographical locality.”

First recorded sometime between 1715–25, morbidity stems from morbid. The first known use of morbid dates back much earlier, sometime around 1650 and stems from the Latin word morbidus (“sickly”).

Keep in mind that while morbidity relates to health, its use does not imply risk of death. For that, you need a different word.

What does mortality mean?

The word mortality is just as dark, but it doesn’t refer to our mental state or a disease. Instead, this noun means “the state or condition of being subject to death; mortal character, nature, or existence.”

For example, people often start thinking about their own mortality before putting together a will.

It can also refer to a specific death rate as in “the relative frequency of deaths in a specific population; death rate.” An example of this would be the compound noun mortality rate, which is in the news lately regarding the coronavirus, which has a higher mortality rate than that of the flu.

Mortality can also refer to “death or destruction on a large scale from war, plague, or famine.” So if an atomic bomb were to go off in a city today, a high mortality would be expected as a result.

Mortality can also finally be defined “as mortal beings collectively, or humanity.”

This grim word originates around 1300–50 from the Middle English mortalite and Latin mortālitās.

How to use these words

To recap: if someone’s mental state is in question or being described, stick to morbidity. Morbidity can also refer to a state of disease in an individual or community.

For example:

  • After the war, the writer seemed to embrace morbidity and his works became quite disturbing.
  • Minimally invasive surgery decreases morbidity associated with this type of injury.
  • The increase in morbidity among low-income adults is concerning.

Morbidity and mortality can be related. For example, here is another version of an example used above: Minimally invasive surgery decreases morbidity and mortality associated with this type of injury. The surgery decreases the risk of disease and the risk of dying.

The key is to remember mortality is related to death.

Here are some additional examples:

  • The mortality rate reveals how many died due to the flu last year.
  • Her father started thinking seriously about his own mortality during a midlife crisis.
  • Cardiovascular disease is a leading cause of mortality among adults.

Medical practitioners are familiar with both these words and likely use them more regularly than most of us, as they must consider the morbidity and mortality of their patients.