tri·​halo·​meth·​ane (ˌ)trī-ˌha-lə-ˈme-ˌthān How to pronounce trihalomethane (audio)
 British usually  -ˈmē-
: any of various derivatives CHX3 of methane (such as chloroform) that have three halogen atoms per molecule and are formed especially during the chlorination of drinking water

Examples of trihalomethane in a Sentence

Recent Examples on the Web Among the chemicals cited in the lawsuit was TTHM, an abbreviation for total trihalomethane. Stephen Hudak, Orlando Sentinel, 3 Apr. 2023 The bureau advises us to filter our tap water because of carcinogenic chloramines and trihalomethane that are in the water as part of the disinfection process, as well as heavy metals that are picked up in the pipes on the way to homes. oregonlive, 25 Apr. 2020 The water was verified to have high levels of TTHM, total trihalomethanes, which can cause multiple medical complications if consumed in large amounts. Detroit Free Press, 20 Apr. 2020 Multiple municipal tests over the years show water in Martin County exceeds the maximum contaminant level for trihalomethane and haloacetic acid, both byproducts of the water’s treatment and both carcinogenic. April Johnston,, 26 Dec. 2019 But Veolia has said it was only hired by the city to assess bacteria and harmful chlorine compounds (trihalomethanes) in Flint’s water supply, not lead. Wired, 13 Dec. 2019 In Dos Palos, where the water contains potentially harmful chemicals known as trihalomethanes, Joaquin Garcia has 5-gallon jugs of clean water delivered to his home. Dale Kasler, Phillip Reese and Ryan Sabalow, sacbee, 1 June 2018 And not only lead, but trihalomethane (TTHM) – a chemical byproduct of chlorine disinfectant. Richard Horan, The Christian Science Monitor, 10 July 2018 Until several months ago, customers received notices on the back of their water bills stating that their water had been tested and found to be above federal limits of trihalomethanes and haloacetic acids. Nadia Kounang, CNN, 30 Mar. 2018

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'trihalomethane.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1968, in the meaning defined above

Time Traveler
The first known use of trihalomethane was in 1968

Dictionary Entries Near trihalomethane

Cite this Entry

“Trihalomethane.” Dictionary, Merriam-Webster, Accessed 13 Apr. 2024.

Medical Definition


(ˌ)trī-ˌhā-lə-ˈmeth-ˌān, British usually -ˈmē-ˌthān
: any of various derivatives CHX3 of methane (as chloroform) that have three halogen atoms per molecule and are formed especially during the chlorination of drinking water
abbreviation THM
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