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n. Slang
Something that presents a particular threat to one that is otherwise powerful: Immigration reform turned out to be the senator's kryptonite.

[After Kryptonite, a fictional radioactive mineral (the presence of which weakens the superhero Superman) appearing in Superman comics from 1949 onwards : Krypton, the home planet of Superman where Kryptonite was once found before being scattered in the universe by the planet's destruction (named by American comics writer Jerry Siegel (1914-1996), perhaps after the element krypton) + -ite.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


informal something that renders a person or thing helpless: football movies are box-office kryptonite.
[C20: from the fictional substance to which the hero is vulnerable in the comic strip Superman]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
Occasionally Oliver works with watchmakers and artisans to make one of a kind, one of one watches - the first being the Kryptonite X Tourbillion watch.
Their 12th place in the table wouldn't mark them down as perennial dangers to City, but they have been kryptonite to Guardiola's side, from that goalless draw in south London last season to the 3-2 win at the Etihad in December.
ANTHONY CROLLA has promised to provide the kryptonite that will ruin the image of boxing's Superman on Hollywood's doorstep.
Les nouveaux sieges, au maintien [beaucoup moins que]confort-fit[beaucoup plus grand que], sont habilles d'une sellerie cuir et AlcantaraA surpiquee de Kryptonite et de Noir Onyx.
ANTHONY CROLLA has promised to provide the Kryptonite that will break down boxing's Superman on Hollywood's doorstep in seven weeks' time.
OKLAHOMA CITY Horses continue to arrive and take up their seasonal residency at Remington Park for the upcoming 2018 thoroughbred season.<br />On Thursday, Kryptonite posted the first official workout of preseason training.<br />Trained by Veronica Griggs of Jones, Kryptonite worked a half-mile handily in 50.53 seconds over a fast track.
2 MAN CITY.......1 SHAKHTAR DONETSK found the Kryptonite to bring Pep Guardiola's supermen to their knees.
We were then presented with their extremely creative menu, in addition to, welcome drinks that are named after our favorite villains the Joker and Kryptonite. The Joker may be a little dark but it will put a smile on your face with its kiwi and apple mix, while Kryptonite is a gift to earth in the form of a refreshing green twist of lemon mint.
L-Corp's CEO was arrested when the National City Police Department obtained a surveillance video showing Lena securing a synthetic Kryptonite, which Metallo used to break out of prison.
Star guard Paul Lee has been super the first two games of the semifinals series but in Game 3, he found his kryptonite in Barangay Ginebra's defense.
We previously described augmentation of wire cerclage sternal closure using "Kryptonite" bone cement (Doctors Research Group Inc.; Southbury, CT) in an effort to reduce the risk of sternal nonunion and accelerate postoperative recovery [2-4].
and Kryptonite, a muddled storyline makes it hard to root for either superhero.