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When you’re not dead yet, but aren’t feeling well either, there’s an EarthWord for that...

EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

Image shows a fish in a tank beneath a half-circle shelter
Sometimes fish display morbidity by not evading predators fast enough. Credit: Megan Cox, St. Cloud State University.

The EarthWord: Morbidity


  • Morbidity isn’t when you have gallows humor, but rather when an organism is diseased or ill for any cause.

  • It can also refer to the percentage of a group that is diseased, i.e., a cave with bats where three quarters of them have been infected with white-nose syndrome has a morbidity of 75%.

  • Morbidity can result from infectious diseases, exposure to contaminants, lack of nutrients, etc.

  • Morbidity can lead to death, but does not have to.


  • Morbidity comes from the Latin word morbus, which meant “sick,” or “diseased.”

Use/Significance in the Earth Science Community:

  • Morbidity is an important concept in both epidemiology and toxicology, as it’s a key indicator of the presence of either an infectious disease or exposure to toxic contaminants.


Next EarthWord: “Whatcha gonna do when they come for you”-thinks this week’s EarthWord...

Hungry for some science, but you don’t have time for a full-course research plate? Then check out USGS Science Snippets, our snack-sized science series that focuses on the fun, weird, and fascinating stories of USGS science.

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