Definition of axion in English:

axion

noun

Physics
  • A hypothetical subatomic particle postulated to account for the rarity of processes that break charge-parity symmetry. It is very light, electrically neutral, and pseudoscalar.

    • ‘This has helped to promote particle-DM, with candidates such as axions, neutralinos and other cold DM particles, as well as warm DM, and self-interacting DM, whose nature is not even specified.’
    • ‘Axions, if they exist at all, do so in our ordinary dimensions, but they are stable neutral particles.’
    • ‘Or another candidate is an even more exotic particle called the axion.’

Origin

1970s: from axial + -on.

Pronunciation:

axion

/ˈaksēˌän/