eta particle. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.

The American Heritage^® Dictionary of the English Language: Fourth Edition. 2000.

eta particle

NOUN:	An electrically neutral meson having a mass 1,071 times that of the electron and a mean lifetime of approximately 3.5 × 10^-⁸ seconds. See table at subatomic particle.


The American Heritage^® Dictionary of the English Language, Fourth Edition. Copyright © 2000 by Houghton Mifflin Company. Published by the Houghton Mifflin Company. All rights reserved.