geo·​smin jē-ˈō-smən How to pronounce geosmin (audio)
plural geosmins
: a volatile, organic compound C12H22O that is formed especially by soil-dwelling bacteria (such as streptomyces) and aquatic cyanobacteria and that may contribute to the earthy, pleasant odor of petrichor or impart a disagreeable, musty taste and odor to drinking water and certain fish
In the test kitchen, we too have noticed a mysterious muddy flavor in some catfish and tilapia. … When the fish swim in the geosmin-rich water, they consume the compound as they ingest the algae.Cook's Illustrated
Geosmin can be detected by a human nose at miniscule concentrations, as low as just a few parts per trillion, [Kelley Dearing] Smith said.James Bruggers

Note: Geosmin is a tertiary alcohol having a hydroxyl group (-OH) attached to a carbon atom that has three other carbon atoms attached to it.

Examples of geosmin in a Sentence

Recent Examples on the Web In these field experiments and in the lab, the pungent geosmin, and another compound called 2-methylisoborneol (2-MIB), released by the Streptomyces colonies attracted tiny, six-legged arthropods called springtails in droves, the researchers report last week in the journal Nature Microbiology. Alex Fox, Smithsonian Magazine, 17 Apr. 2020 The geosmin and other petrichor compounds that may be present on the ground or dissolved within the raindrop are released in aerosol form and carried by the wind to surrounding areas. Tim Logan, Discover Magazine, 28 Aug. 2018 But Stensmyr and colleagues then had the flies choose between plain yeast and S. coelicolor that couldn’t produce geosmin. Guest Blogger, Discover Magazine, 7 Mar. 2013 Horticultural scientists have been examining geosmin levels of various beet varieties to breed specialty beets with less of this aromatic compound, such as the Badger Flame varieties developed at the University of Wisconsin. Casey Barber, CNN, 23 Sep. 2021 Streptomyces uses geosmin to ring the dinner bell for hungry springtails, which eat the bacteria, and in return the arthropods spread the bacteria’s spores far and wide. Alex Fox, Smithsonian Magazine, 17 Apr. 2020 Our noses can detect just a few parts of geosmin per trillion of air molecules. Tim Logan, Discover Magazine, 28 Aug. 2018 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'geosmin.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Greek gē-, geō-, combining form of "earth" + osmḗ "odor" + -in entry 1 — more at geo-, anosmia

Note: Term introduced by the American biochemist Nancy N. Gerber (1929-85) and the French-born American biologist Hubert A. Lechevalier (1926-2015) in "Geosmin, an Earthy-Smelling Substance Isolated from Actinomycetes," Applied Microbiology, vol. 13, no. 6 (November, 1965), pp. 935-38.

First Known Use

1965, in the meaning defined above

Time Traveler
The first known use of geosmin was in 1965

Dictionary Entries Near geosmin

Cite this Entry

“Geosmin.” Dictionary, Merriam-Webster, Accessed 3 Dec. 2023.

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