Massive particle

Particle having real positive rest mass

The physics technical term massive particle refers to a massful particle which has real non-zero rest mass, the counter-part to the term massless particle. According to special relativity, the velocity of a massive particle is always less than the speed of light. When highlighting relativistic speeds, the synonyms bradyon, tardyon or ittyon are sometimes used to contrast with luxon and hypothetical tachyon.

This keyword could refer to multiple things. Here are some suggestions: