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
Since arriving in the big leagues, Minnesota Twins starter Joe Ryan has been the Kansas City Royals’ personal kryptonite.
—Kansas City Star, 7 Sep. 2025
John Kosko of Pro Football Focus has identified Jackson's playoff problems as his biggest kryptonite entering the 2025 campaign.
—Matthew Schmidt, MSNBC Newsweek, 28 Aug. 2025
While easily ranking as the top-grossing comic book movie of the year so far, Superman hasn’t been able to escape kryptonite altogether as superhero fatigue continues to make audiences more discerning.
—Pamela McClintock, HollywoodReporter, 22 Aug. 2025
Real suffering is kryptonite to rich-people-problems entertainment (which is probably also why The Real Housewives of New York City imploded, this past January, in a season finale where one cast member accused another of insensitivity towards the former’s traumatic experience as a rape survivor).
—Judy Berman, Time, 13 Aug. 2025
See All Example Sentences for kryptonite
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Kansas City Star, 7 Sep. 2025
John Kosko of Pro Football Focus has identified Jackson's playoff problems as his biggest kryptonite entering the 2025 campaign.
—Matthew Schmidt, MSNBC Newsweek, 28 Aug. 2025
While easily ranking as the top-grossing comic book movie of the year so far, Superman hasn’t been able to escape kryptonite altogether as superhero fatigue continues to make audiences more discerning.
—Pamela McClintock, HollywoodReporter, 22 Aug. 2025
Real suffering is kryptonite to rich-people-problems entertainment (which is probably also why The Real Housewives of New York City imploded, this past January, in a season finale where one cast member accused another of insensitivity towards the former’s traumatic experience as a rape survivor).
—Judy Berman, Time, 13 Aug. 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 10 Sep. 2025.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
Share