noun ax·ion \ˈak-sē-(ˌ)än\

Definition of axion

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

Origin and Etymology of axion

axial + 2-on

First Known Use: 1978

Seen and Heard

What made you want to look up axion? Please tell us where you read or heard it (including the quote, if possible).