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
Traveling is no longer a kryptonite for Rachel Brosnahan, thanks to the help of a witch.
—EW.com, 17 July 2025
These tend to involve kryptonite, the substance that weakens the hero.
—Matt Zoller Seitz, Vulture, 16 July 2025
The Dodgers have been the Braves' kryptonite this season, having won all five games against them.
—Ben Verbrugge, MSNBC Newsweek, 4 May 2025
While there were a few memorable scenes, the script is its kryptonite.
—Billie Melissa, MSNBC Newsweek, 8 July 2025
See All Example Sentences for kryptonite
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EW.com, 17 July 2025
These tend to involve kryptonite, the substance that weakens the hero.
—Matt Zoller Seitz, Vulture, 16 July 2025
The Dodgers have been the Braves' kryptonite this season, having won all five games against them.
—Ben Verbrugge, MSNBC Newsweek, 4 May 2025
While there were a few memorable scenes, the script is its kryptonite.
—Billie Melissa, MSNBC Newsweek, 8 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 29 Jul. 2025.
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