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 Posnanski
Ironic 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 Parch
Effortlessly good-looking, he was also a talented writer—that combo was my kryptonite.Taylor Orci

Examples of kryptonite in a Sentence

Recent Examples on the Web His pitch location was has been his kryptonite in three starts (5.87 ERA), largely mistakes over the middle. Sam Cohn, Baltimore Sun, 13 Apr. 2024 To hear Gilbert tell it, Gauff’s kryptonite is not her forehand. Abby Aguirre, Vogue, 6 Mar. 2024 Instead, the failure of AI to deliver as big or fast as Wall Street deems may prove the kryptonite that busts the blast. Shawn Tully, Fortune, 28 Feb. 2024 Fox News finally reveals its kryptonite: the bottom line: Years of moral outrage from watchdog groups failed to change the network’s course. Los Angeles Times, 3 Mar. 2023 Then came the aftershock of soaring interest rates — kryptonite for an industry built on debt. Matthew Haag, New York Times, 28 Dec. 2023 Metal and even water are like kryptonite for the wireless waves used in WiFi, but even shelves and books can get in the way. Geoffrey A. Fowler, Washington Post, 20 Dec. 2023 Staud Shoko Sweater Dress, $124 (Save $41) Snag the Staud Shoko Sweater Dress, which is like cozy clothing kryptonite for Kate Middleton and Taylor Swift since they’re repeat wearers of the trend. Alyssa Grabinski, Peoplemag, 28 Sep. 2023 Or there was that time last year when the Yankees barely survived five games in the ALDS against Cleveland and then got dominated in a sweep by the Astros, a team known as the Yankee kryptonite. Larry Fleisher, Forbes, 13 Nov. 2023

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 15 Jun. 2024.

Last Updated: - Updated example sentences
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