tachyon

noun Physics.

1. a hypothetical particle that travels faster than the speed of light.

noun

1. physics a hypothetical elementary particle capable of travelling faster than the velocity of light

n.1967, hypothetical faster-than-light particle, from tachy- “swift” + -on.

1. A hypothetical subatomic particle that travels faster than the speed of light. Although the principles of relativity forbid the acceleration of a particle past the speed of light, they do not prohibit the existence of particles that have always moved faster than that speed. No such particle has ever been detected.