kryptonite
noun
kryp·to·nite
ˈkrip-tə-ˌnīt 
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.Tom RussoIn his career Thome has hit less than .240 against lefties. Lefthanded power pitching is Thome's Kryptonite …—Joe Posnanski
Joe PosnanskiIronic people always dissolve when confronted with earnestness, it's their kryptonite.—Gillian Flynn
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
Lorie ParchEffortlessly good-looking, he was also a talented writer—that combo was my kryptonite.—Taylor Orci
Taylor OrciExamples of kryptonite in a Sentence
Recent Examples on the Web
The finding now gives scientists the chance to discover the kryptonite that will sap them of this extra boost of strength.
—New Atlas, 3 Aug. 2025
Over the weekend, Warner Bros.’ Superman fought off the box-office kryptonite of declining theatrical attendance and creeping superhero fatigue to soar to $125 million in North American ticket sales.
—Chris Lee, Vulture, 14 July 2025
Daniel: Superman’s biggest weakness would become the mineral kryptonite, but before that, his biggest limitation was being fictional.
—Ari Daniel, Smithsonian Magazine, 10 July 2025
In order to keep Superman's nose out of his business, he's impregnated the whole thing with kryptonite.
—Richard Edwards, Space.com, 10 July 2025
See All Example Sentences for kryptonite
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New Atlas, 3 Aug. 2025
Over the weekend, Warner Bros.’ Superman fought off the box-office kryptonite of declining theatrical attendance and creeping superhero fatigue to soar to $125 million in North American ticket sales.
—Chris Lee, Vulture, 14 July 2025
Daniel: Superman’s biggest weakness would become the mineral kryptonite, but before that, his biggest limitation was being fictional.
—Ari Daniel, Smithsonian Magazine, 10 July 2025
In order to keep Superman's nose out of his business, he's impregnated the whole thing with kryptonite.
—Richard Edwards, Space.com, 10 July 2025
See All Example Sentences for kryptonite
Cite this Entry
“Kryptonite.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/kryptonite. Accessed 15 Aug. 2025.
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