noun Physics, Astronomy.
radiation consisting of atomic and subatomic particles, as alpha particles, beta particles, and neutrons.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Radiation consisting of streams of subatomic particles such as protons, electrons, and neutrons.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.