dieldrin
noun
diel·drin ˈdēl-drən 
: a white crystalline persistent toxic chlorinated compound C12H8Cl6O used especially formerly as an insecticide
Example Sentences
Recent Examples on the Web As a result of a lawsuit filed by the fund in Michigan, nearly every city stopped using DDT, and an application of another pesticide, dieldrin, in Western Michigan, to fight Japanese beetles, was delayed for a year. 
Richard Sandomir, New York Times, 18 Feb. 2022 Many are also insusceptible to later pesticides like dieldrin, malathion and deltamethrin. Charles C. Mann, WSJ, 26 Apr. 2018 The environmental assessment found the presence of toxaphene and dieldrin, decades-old insecticides that are now banned and have been shown to cause cancer in mice. Skyler Swisher, Sun-Sentinel.com, 10 Apr. 2018
Richard Sandomir, New York Times, 18 Feb. 2022 Many are also insusceptible to later pesticides like dieldrin, malathion and deltamethrin. Charles C. Mann, WSJ, 26 Apr. 2018 The environmental assessment found the presence of toxaphene and dieldrin, decades-old insecticides that are now banned and have been shown to cause cancer in mice. Skyler Swisher, Sun-Sentinel.com, 10 Apr. 2018 Word History
Etymology
Diels-Alder reaction (an addition reaction forming a 6-membered ring), after Otto Diels & Kurt Alder
First Known Use
circa 1949, in the meaning defined above
Medical Definition
dieldrin
noun
diel·drin ˈdē(ə)l-drən
: a white crystalline persistent chlorinated hydrocarbon insecticide C12H8Cl6O