axion

noun

ax·​ion ˈak-sē-(ˌ)än 

: a hypothetical subatomic particle of low mass and energy that is postulated to exist because of certain properties of the strong force

Examples of axion in a Sentence

Recent Examples on the Web

For example, extremely light particles, such as axions or special types of photons considered candidates for dark matter, could absorb the rotational energy of black holes, amplifying their signals. —Manon Bischoff, Scientific American, 12 May 2025

This axion quasiparticle is designed in such a way that its frequency can be transmitted into space using a much larger piece of axion quasiparticle material — a frequency that would hopefully match up with actual axions. —Robert Lea, Space.com, 16 Apr. 2025

However, Balaji and colleagues have mostly ruled out axions and axion-like particles as their dark matter culprits linked to the ionization of gas in the CMZ. —Robert Lea, Space.com, 10 Mar. 2025

Currently, the leading suspect for dark matter particles are axions, which have remained frustratingly hypothetical. —Robert Lea, Space.com, 27 Feb. 2025

Word History

Etymology

axi(al) + -on entry 2

Note: The name axion was introduced by the American physicist Stephen Weinberg (born 1933) in "A New Light Boson?", Physical Review Letters, vol. 40, no. 4 (January 23, 1978), p. 233; and by American physicist Frank Wilczek (born 1951) in "Problems of Strong P and T Invariance in the Presence of Instantons," Physical Review Letters, vol. 40, no. 5, p. 279. In an article in the online journal Quanta, "Time's (Almost) Irreversible Arrow" (January 7, 2016), Frank Wilczek explained the coinage as follows: "A few years before [in 1977], a supermarket display of brightly colored boxes of a laundry detergent named Axion had caught my eye. It occurred to me that 'axion' sounded like the name of a particle and really ought to be one. So when I noticed a new particle that 'cleaned up' a problem with an 'axial' current, I saw my chance. (I soon learned that Steven Weinberg had also noticed this particle, independently. He had been calling it the 'Higglet.' He graciously, and I think wisely, agreed to abandon that name.) Thus began a saga whose conclusion remains to be written."

First Known Use

1978, in the meaning defined above