Kryptonite

//ˈkɹɪptənaɪt// noun, verb, slang

noun, verb, slang ·Moderate ·College level

Definitions

Noun
  1. 1
    The one weakness of something or someone that is otherwise invulnerable. figuratively, uncountable, usually

    "The terrific seven-grain bread here is the kryptonite of restaurant reviewers: two mini-loaves and you are incapacitated."

  2. 2
    Crack cocaine. slang, uncountable, usually
Verb
  1. 1
    To expose to, or attack with, kryptonite.

    "And even those two were pretty puny, like Superman after he had been kryptonited."

  2. 2
    To destroy, wreck, or ruin; to affect adversely, as Superman is affected by kryptonite. figuratively

Synonyms

All synonyms
achilles heelchink in the armorglass jawsoft spotsoft underbellyvulnerability

Example

More examples

"Commitment is like kryptonite to Tom."

Etymology

From a fictional radioactive element, kryptonite, that has a detrimental effect on the otherwise invulnerable character Superman. Apparently formed as krypton (“a chemical element, Kr”) + -ite.

Related phrases

achilles heel

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.