cacodylic acid

noun

cac·​o·​dyl·​ic acid ˌka-kə-ˈdi-lik- How to pronounce cacodylic acid (audio)
: a toxic crystalline compound of arsenic C2H7AsO2 used especially as an herbicide

Word History

Etymology

German Kakodyl, the radical (CH3)2As + -ic entry 1; Kakodyl from Greek kakṓdēs "foul-smelling" (from kakós "bad, ill, foul" + -ōdēs "having a given smell," adjective derivative from od-, the base of ózein "to smell, give off odor") + German -yl -yl — more at caco-, odor

Note: According to Jöns Jakob berzelius, he suggested the name Kakodyl to the chemist Robert bunsen, who was investigating it, because of "the extremely repellent smell of all of its compounds" ("… für welche ich Bunsen den Namen Kakodyl vorschlug, in Bezug auf den höchst wiedrigen Geruch aller seiner Verbindungen" - Jahresbericht über die Fortschritte der physischen Wissenschaften von Jacob Berzelius, 20. Jahrgang [1841], p. 527).

First Known Use

1840, in the meaning defined above

Time Traveler
The first known use of cacodylic acid was in 1840

Rhymes for cacodylic acid

See All Rhymes for cacodylic acid

Browse Nearby Words

cacodoxy
cacodylic acid
cacodyl oxide
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Cite this Entry

“Cacodylic acid.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cacodylic%20acid. Accessed 6 Jul. 2026.

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Medical Definition

cacodylic acid

noun
cac·​o·​dyl·​ic acid ˌkak-ə-ˌdil-ik- How to pronounce cacodylic acid (audio)
: a toxic crystalline compound of arsenic C2H7AsO2 used especially as an herbicide
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