chlorpyrifos

noun

chlor·​pyr·​i·​fos klȯr-ˈpir-ə-fäs 

-ˈpī-rə

: a toxic crystalline organophosphate pesticide C₉H₁₁Cl₃NO₃PS that inhibits acetylcholinesterase and is used to control insect pests and ticks

Examples of chlorpyrifos in a Sentence

Recent Examples on the Web

No products from Corteva or BASF were included in the study linking chlorpyrifos to Parkinson’s disease. — Angelica Stabile, FOXNews.com, 23 Mar. 2026

Before it was banned, more than 900,000 pounds of chlorpyrifos were used in 2017— more than in any other state. — Melissa Gomez, Los Angeles Times, 30 Sep. 2024

Internationally, the fate of chlorpyrifos remains an open question. — Sharon Lerner, ProPublica, 6 July 2023

Those limits -- and development of replacement pest controls -- have led to a decline in farmers’ use of chlorpyrifos, EPA said. — John Flesher, chicagotribune.com, 18 Aug. 2021

Word History

Etymology

chlor- + pyridine + -fos (alteration of phosphorus)

First Known Use

1970, in the meaning defined above

Medical Definition

chlorpyrifos

noun

chlor·​pyr·​i·​fos -ˈpir-ə-fäs, -ˈpī-rə- 

: a toxic crystalline organophosphate pesticide C₉H₁₁Cl₃NO₃PS that inhibits acetylcholinesterase and is used to control insect pests and ticks