kryptonite

[ krip-tuh-nahyt ]

noun

1. Usually Kryptonite. a fictional radioactive substance that is the only thing capable of hurting or weakening the otherwise invulnerable superhero Superman:

   Exposure to Kryptonite nullifies Superman's powers and immobilizes him with pain.

2. Sometimes Kryptonite. something that a person or thing cannot defend against or defeat; a nemesis or bête noire:

   The team has not found a way to stop the triple option attack, which has been their kryptonite over the last several years.

   Garlic oil is kryptonite for aphids.

Word History and Origins

Origin of kryptonite¹

Coined in 1943 by writer and producer George Lowther (1913–1975); krypton ( def ) + -ite ¹( def )

Example Sentences

Or Britney Spears kicking her way out of a block of Kryptonite in 1999?

From BBC

The term is such electoral kryptonite that a recently released study by researchers at Harvard and Georgetown found that politicians who use “Latinx” turn off Latino voters instead of attracting them.

From Los Angeles Times

But the specter of 2016 looms, and for the same reason it did then: While Trump is ignoring the polls and saying anything he pleases, the Democratic candidate has too often been treating risk like kryptonite and exaggerating the importance of “the issues” while underestimating the importance of perceptions of candidates’ mettle.

From Salon

The actor's injuries are creatively represented by a green substance - clearly meant to resemble kryptonite - seen gradually covering his bones in reconstructed X-rays.

From BBC

If you didn’t know any better — if you hadn’t seen his speeches or interviews with bro-ey podcasts — you might not have caught Vance’s gaslighting, especially on the issue of abortion, which has become ballot box kryptonite for Republicans.

From Los Angeles Times