coumarin
noun
cou·ma·rin
ˈkü-mə-rən 
: a toxic white crystalline lactone C9H6O2 with an odor of new-mown hay found in plants or made synthetically and used especially in perfumery and as a parent compound in anticoagulant agents
also
: a derivative of this compound
Examples of coumarin in a Sentence
Recent Examples on the Web
Cinnamon is generally safe in small amounts, but supplements should be used cautiously due to potential interactions and the presence of coumarin, which can be harmful to people with liver conditions.
—
Karen Shackelford, Verywell Health, 17 June 2025
As long as that coumarin molecule is bound to the drug, which is known as Penicillin-PPG (Photocleavable Protecting Groups), the antibiotic remains inactive.
—Ben Coxworth, New Atlas, 13 June 2025
Wen: Cassia cinnamon may contain high levels of coumarin, which is a blood thinner.
—Katia Hetter, CNN Money, 8 May 2025
But Quattrocchi, who was not affiliated with the study, warned that coumarin can cause liver damage with excessive use.
—Amy McGorry, FOXNews.com, 12 May 2025
Ceylon cinnamon may also have trace amounts of coumarin.
—Katia Hetter, CNN Money, 8 May 2025
Ageratum is an annual flower that secretes coumarin (used in commercial mosquito repellents), which has an odor that mosquitoes can’t stand.
—Clarence Schmidt, San Diego Union-Tribune, 11 Apr. 2024
Alongside is a sidecar of vanilla-tonka bean maple syrup, heady with the almond-y, fresh-hay scent of coumarin — a naturally occurring chemical in the seeds of the kumaru tree.
—Stephanie Breijo, Los Angeles Times, 3 Nov. 2024
In any case, chamomile flowers—which look like adorable, tiny daisies—contain flavonoids, terpenoids, and coumarins which certainly have mildly sedative, anti-inflammatory, and antispasmodic properties.
—Valentina Bottoni, Vogue, 23 Oct. 2024
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Karen Shackelford, Verywell Health, 17 June 2025
As long as that coumarin molecule is bound to the drug, which is known as Penicillin-PPG (Photocleavable Protecting Groups), the antibiotic remains inactive.
—Ben Coxworth, New Atlas, 13 June 2025
Wen: Cassia cinnamon may contain high levels of coumarin, which is a blood thinner.
—Katia Hetter, CNN Money, 8 May 2025
But Quattrocchi, who was not affiliated with the study, warned that coumarin can cause liver damage with excessive use.
—Amy McGorry, FOXNews.com, 12 May 2025
Ceylon cinnamon may also have trace amounts of coumarin.
—Katia Hetter, CNN Money, 8 May 2025
Ageratum is an annual flower that secretes coumarin (used in commercial mosquito repellents), which has an odor that mosquitoes can’t stand.
—Clarence Schmidt, San Diego Union-Tribune, 11 Apr. 2024
Alongside is a sidecar of vanilla-tonka bean maple syrup, heady with the almond-y, fresh-hay scent of coumarin — a naturally occurring chemical in the seeds of the kumaru tree.
—Stephanie Breijo, Los Angeles Times, 3 Nov. 2024
In any case, chamomile flowers—which look like adorable, tiny daisies—contain flavonoids, terpenoids, and coumarins which certainly have mildly sedative, anti-inflammatory, and antispasmodic properties.
—Valentina Bottoni, Vogue, 23 Oct. 2024
Cite this Entry
“Coumarin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/coumarin. Accessed 19 Jul. 2025.
Copy CitationMedical Definition
coumarin
noun
cou·ma·rin
ˈkü-mə-rən
: a toxic white crystalline lactone C9H6O2 with an odor of new-mown hay found in plants or made synthetically and used especially in perfumery and as the parent compound in various anticoagulant agents (as warfarin)
also
: a derivative of this compound
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