A particle is

1. In particle physics, a basic unit of matter or energy.
2. In colloid chemistry , a colloidal particle - phase colloid or molecular colloid
3. In ecology, a small object of nonbiological kind.
4. In linguistics, a grammatical particle.
5. In computer graphics, an element of a particle system (simulation).
6. In common use: a very small to insignificant amount. See also grain.
7. In music, the band Particle
8. In wave physics Particle displacement
9. In acoustics Sound particle velocity