Definition of kryptonite in English:

kryptonite

noun

mass noun
  • 1(in the fictional word of the cartoon, TV, and film character Superman) an alien mineral that has the property of depriving Superman of his powers.

    ‘the evil Lex Luthor diminishes Superman's powers with kryptonite’
    • ‘Remember when polystyrene foam was environmental kryptonite?’
    • ‘‘It's kryptonite for both sides,’ one travelling official said, and in a exquisitely poised contest like this, neither wants to risk disaster.’
    • ‘But it's the snacking, even on so-called ‘healthy foods,’ in between meals that's my kryptonite.’
    • ‘Did the Raiders uncover Pennington's kryptonite?’
    • ‘These things are like kryptonite to terrorists.’
    1. 1.1 Something that can seriously weaken or harm a particular person or thing.
      ‘flip-flopping on issues can be kryptonite to presidential candidates’
      ‘such uncertainties are kryptonite for the bond market’

Origin

1940s: from Krypton, the name of Superman's home planet (kryptonite is usually depicted as a green mineral that came to earth from Krypton, following its destruction).

Pronunciation

kryptonite

/ˈkrɪptənʌɪt/