1. a hypothetical atom composed of antimatter, with the same structure as a normal atom but with antiparticles replacing ordinary particles.
Usage: physics; theoretical

Examples

• Scientists theorize that an antiatom would annihilate upon contact with ordinary matter.
• The study of antiatoms helps physicists understand the nature of antimatter.
• An antiatom of hydrogen would consist of a positron orbiting an antiproton.
• Researchers have attempted to create and observe antiatoms in particle accelerators.
• The properties of an antiatom mirror those of its matter counterpart.