thallium

noun

thal·​li·​um ˈtha-lē-əm 

: a soft poisonous metallic element that resembles lead in physical properties, occurs sparsely in a number of common ores, and is used chiefly in the form of compounds especially in photosensitive devices and formerly as a pesticide see Chemical Elements Table

Examples of thallium in a Sentence

Recent Examples on the Web

Testing by the utility identified selenium and thallium in the effluent there. —Connor Giffin, The Courier-Journal, 23 Jan. 2024

But the spotlight naturally pulls back to Beck, whose eidetic memory for faces, locations and even a stray box of thallium salts at the crime scene suggests a level of expertise honed in places far beyond Lincoln County. —Paula L. Woods, Los Angeles Times, 18 July 2023

While other metals such as nickel, thallium and lead were more likely to exceed those EPA markers in poorer, less-white communities like Rose Park, arsenic was more concentrated in samples from wealthy communities, possibly because of its past use as a fertilizer on agricultural lands. —Evan Bush, NBC News, 7 Dec. 2022

Check out thallium and tungsten. —Ed Yong, Discover Magazine, 24 Sep. 2011

Word History

Etymology

New Latin, from Greek thallos green shoot; from the bright green line in its spectrum

First Known Use

1861, in the meaning defined above

Kids Definition

thallium

noun

thal·​li·​um ˈthal-ē-əm 

: a soft poisonous metallic element that has characteristics similar to lead see element

Medical Definition

thallium

noun

thal·​li·​um ˈthal-ē-əm 

: a sparsely but widely distributed poisonous metallic element that resembles lead in physical properties and is used chiefly in the form of compounds in photoelectric cells or as a pesticide

—symbol Tl see Chemical Elements Table