Dictionary.com
Thesaurus.com

eta particle

American  

noun

  1. Physics. a meson with a neutral charge, a mass 1,071 times that of the electron, and an approximate mean lifetime of 3.5 × 10-8 seconds.

eta particle Scientific  
/ ā′tə,ē′tə /

  1. 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.

  2. See Table at subatomic particle

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.