Definition of kryptonite in English:

kryptonite

noun

  • [mass noun] (in science fiction) an alien mineral with the property of depriving Superman of his powers.

    figurative ‘girls of her sort are kryptonite to the developing hearts of adolescent boys’
    • ‘Did the Raiders uncover Pennington's kryptonite?’
    • ‘But it's the snacking, even on so-called ‘healthy foods,’ in between meals that's my 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.’
    • ‘These things are like kryptonite to terrorists.’

Pronunciation:

kryptonite

/ˈkrɪptənʌɪt/