Main Entry: elementary particle

Function: noun

1 : any of the particles of which matter and energy are composed or which mediate the fundamental forces of nature ; especially : one (as the photon or the electron) whose existence has not been attributed to the combination of other more fundamental entities
2 : one of the structural units of mitochondrial cristae that are observable by the electron microscope usually as spheres or stalked spheres and are probably the seat of fundamental energy-producing reactions