# tachyon

> English word · Noun · IPA /ˈtæk.i.ɒn/ · frequency rank #74,558

## Definitions
1. A hypothetical particle that travels faster than the speed of light.
2. A flaw in a physical theory that predicts the existence of tachyons or similar paradoxical results. Compare with ghost.

## Etymology
Formed as: tachy- + -on, from ταχύς (takhús, “swift”, “rapid”).
Coined by American physicist Gerald Feinberg in 1967.

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