Meaning of subnuclear particle

sub•nu'cle•ar par'ticle

Pronunciation: (sub-n'klē-ur, -ny'- or, by metathesis, -kyu-lur) [key]
— Physics. Physics.
  1. any of the elementary particles, including those that do not exist in stable matter but appear as a result of high-energy collisions of other particles or nuclei.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.