thal·​li·​um | \ ˈtha-lē-əm How to pronounce thallium (audio) \

Definition of thallium

: 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 Someone used a rare toxic metal called thallium to fell the once-powerful and athletic lobbyist, reporter Nigel Jaquiss writes in his detailed account. The Oregonian/oregonlive Politics Team, oregonlive, 3 Nov. 2021 Many notable revolutionaries are associated with equally notable facial hair—from Emiliano Zapata and Karl Marx to Fidel Castro, whose beard was so iconic that the C.I.A. wanted to remove it, via thallium salts in his shoes. Rachel Lipstein, The New Yorker, 23 Apr. 2020 Specifically, the group says the creek has shown signs of elevated concentrations of mercury, and elevated levels of arsenic, molybdenum, selenium, copper and thallium from mining in the area. William Thornton |, al, 1 Mar. 2020 That volcano emits fumes with a thallium concentration at least ten times higher than any other volcanic vapors ever studied. Sophia Chen, WIRED, 1 July 2019 The substance that condensed inside the tube, upon analysis, contained an abnormally large amount of thallium. Sophia Chen, WIRED, 1 July 2019 But a second hair from March 1995 showed Zhu Ling had ingested large doses of thallium constantly for about two weeks. Jennifer Ouellette, Ars Technica, 25 Dec. 2018 Ash found that Zhu Ling had received many doses of toxic thallium, increasing in frequency and concentration over time. Jennifer Ouellette, Ars Technica, 25 Dec. 2018 Lead, arsenic, boron, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, selenium, thallium, and uranium are among the chemicals and heavy metals listed with coal ash deposits. Grace Schneider, The Courier-Journal, 18 May 2018 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'thallium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of thallium

1861, in the meaning defined above

History and Etymology for thallium

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

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The first known use of thallium was in 1861

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Cite this Entry

“Thallium.” Dictionary, Merriam-Webster, Accessed 3 Jul. 2022.

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More Definitions for thallium


thal·​li·​um | \ ˈthal-ē-əm How to pronounce thallium (audio) \

Medical Definition of thallium

: 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

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