# toponium

> English word · Noun

## Definitions
1. Any hypothetical meson formed from a top quark and its antiquark; would be very unstable because of the large mass of the top quark

## Etymology
From top + -onium. From top quark and "-onium" as in positronium.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/toponium