[ an-tee-at-uh m, an-tahy- ]
/ ˈæn tiˌæt əm, ˈæn taɪ- /

noun Physics.

an atom of antimatter.

Origin of antiatom

First recorded in 1965–70; anti- + atom Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Science definitions for antiatom

[ ăntē-ăt′əm, ăn′tī- ]

An atom composed of antiparticles. An antiatom consists of positrons, antiprotons, and antineutrons. It has the same mass and spin as an ordinary atom, and the same amount of charge and magnetic moment, but the charge and magnetic moment are the opposite of those of an ordinary atom.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.