warfarin

noun

war·​fa·​rin ˈwȯr-fə-rən 

: a crystalline anticoagulant coumarin derivative C₁₉H₁₆O₄ that inhibits the production of prothrombin by vitamin K and is used as a rodent poison and in medicine

also : its sodium salt C₁₉H₁₅NaO₄ used especially in the prevention or treatment of thromboembolic disease

Examples of warfarin in a Sentence

Recent Examples on the Web

Large changes in dietary or supplemental vitamin K intake can change how well warfarin works. — Sara Hoffman, Verywell Health, 27 May 2026

There's conflicting research about whether cranberry interacts with the blood thinner Coumadin (warfarin). — Cynthia Sass, Health, 27 Apr. 2026

For those on blood thinners like warfarin, taking noni with your medication can also reduce your body’s blood-clotting ability. — Bestreviews, Mercury News, 10 Feb. 2026

For nearly 60 years, the drug of choice was warfarin, which was originally developed as a rat poison. — David Cox, NBC news, 5 Feb. 2026

Word History

Etymology

Wisconsin Alumni Research Foundation (its patentee) + coumarin

First Known Use

1950, in the meaning defined above

Medical Definition

warfarin

noun

war·​fa·​rin ˈwȯr-fə-rən 

: a crystalline anticoagulant coumarin derivative C₁₉H₁₆O₄ related to dicumarol that inhibits the production of prothrombin by vitamin K and is used as a rodent poison and in medicine

also : its sodium salt C₁₉H₁₅NaO₄ used especially in the prevention or treatment of thromboembolic disease see coumadin