A very small piece of matter, a fragment; especially, the smallest possible part of something.

plural of particle

A tiny piece of radioactive material that can become lodged in living tissue.

plural of hot particle

A device that accelerates electrically charged particles to extremely high speeds, for the purpose of inducing high energy reactions or producing high energy radiation.

(physics) A positively charged nucleus of a helium-4 atom (consisting of two protons and two neutrons), emitted as a consequence of radioactivity; α-particle

(physics) An energetic electron or positron produced as the result of a nuclear reaction or nuclear decay.

(informal) The Higgs boson.

Any of many units of matter smaller than an atom.

(US, Canada) a structural material manufactured from wood particles (such as chips and shavings) by pressing, and binding through resin