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
Example Sentences
Recent Examples on the Web This latest version of the scent reportedly features top notes of lavender and bergamot, middle notes of jasmine, iris, and rose, and base notes of vanilla, sandalwood, coumarin, benzoin, licorice, and patchouli. 
Marci Robin, Allure, 4 Aug. 2019 Galium odoratum owes its sweet scent to the odiferous agent coumarin. Earl Nickel, SFChronicle.com, 8 June 2018 Cassia can contain relatively high concentrations of coumarin, a plant compound that can damage the liver. Sandee Lamotte, CNN, 8 Mar. 2018 Cassia sticks, which look like a thick layer of rolled bark, also contained 18 times more coumarin than Ceylon sticks, which have thin layers. Sandee Lamotte, CNN, 8 Mar. 2018 Both cassia cinnamon and Saigon cinnamon contain coumarin, a natural compound that can harm the liver when taken in large amounts. Teresa Graedon, The Seattle Times, 21 May 2017
Marci Robin, Allure, 4 Aug. 2019 Galium odoratum owes its sweet scent to the odiferous agent coumarin. Earl Nickel, SFChronicle.com, 8 June 2018 Cassia can contain relatively high concentrations of coumarin, a plant compound that can damage the liver. Sandee Lamotte, CNN, 8 Mar. 2018 Cassia sticks, which look like a thick layer of rolled bark, also contained 18 times more coumarin than Ceylon sticks, which have thin layers. Sandee Lamotte, CNN, 8 Mar. 2018 Both cassia cinnamon and Saigon cinnamon contain coumarin, a natural compound that can harm the liver when taken in large amounts. Teresa Graedon, The Seattle Times, 21 May 2017 Word History
Etymology
French coumarine, from coumarou tonka bean tree, from Spanish or Portuguese; Spanish cumarú, from Portuguese, from Tupi *kumarú, *kumbarú
First Known Use
1830, in the meaning defined above
Medical 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