kryp·​to·​nite ˈkrip-tə-ˌnīt How to pronounce kryptonite (audio)
variants or Kryptonite
in stories
: a substance that causes the comic-book character Superman to become weak when he is exposed to it

Note: In Superman stories, kryptonite in its most familiar form is a green mineral that originated as part of Superman's home planet of Krypton and that falls to Earth as a meteorite.

Superman tended to get more bummed out by Kryptonite than by anything going on in Clark Kent's life …Tom Russo
often used to describe something likened to kryptonite in causing someone's weakness, failure, etc.
In his career Thome has hit less than .240 against lefties. Lefthanded power pitching is Thome's KryptoniteJoe PosnanskiIronic people always dissolve when confronted with earnestness, it's their kryptonite.Gillian Flynn"Thin people know they need to either limit exposure to certain foods that trigger appetite or limit the quantity or frequency of those foods," says Gullo, whose personal kryptonite is pizza.Lorie ParchEffortlessly good-looking, he was also a talented writer—that combo was my kryptonite.Taylor Orci

Example Sentences

Recent Examples on the Web Left-handed pitchers have been a kryptonite of sorts for the Orioles of late, and without Cedric Mullins, Adley Rutschman and Gunnar Henderson in the starting lineup, there was a noticeable lack of power. Andy Kostka, Baltimore Sun, 28 Sep. 2022 Stagflation—high prices accompanied by anemic to negative growth—is the kryptonite of growth stocks. Bernhard Warner, Fortune, 11 Oct. 2021 Can facts and comedy be the kryptonite to Trump and Greene's lies? Dean Obeidallah, CNN, 27 June 2021 While Donald is, without a doubt, the best defender the Cowboys will face on their 2020 schedule, Martin has been proven to be the kryptonite to Donald’s Superman. John Owning, Dallas News, 9 Sep. 2020 The problem: Hopelessness is the kryptonite to your superpower of motivation. Popular Science, 2 June 2020 Humidity is like kryptonite for non-straight hair textures because the moisture in the air helps hair revert back to its natural texture. Jasmine Washington, Seventeen, 10 Jan. 2023 Aidan O’Connell’s kryptonite wears Cardinal and White. Mark Stewart, Journal Sentinel, 23 Oct. 2022 Fields glow kryptonite-green against volcanic black soil, while not-so-distant mountains smoke and spew hot red lava above the heads of hardy sheep. Peter Debruge, Variety, 11 Apr. 2022 See More

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

Word History


Krypton, Superman's home planet + -ite entry 1

First Known Use

1943, in the meaning defined above

Time Traveler
The first known use of kryptonite was in 1943

Dictionary Entries Near kryptonite

Cite this Entry

“Kryptonite.” Dictionary, Merriam-Webster, Accessed 31 Mar. 2023.

Last Updated: - Updated example sentences
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