- any lepton, hadron, photon, or graviton, the particles once thought to be the indivisible components of all matter or radiation.
- any of several entities, such as electrons, neutrons, or protons, that are less complex than atoms and are regarded as the constituents of all matterAlso called: fundamental particle
- A knoblike body that appears on the luminal surfaces of mitochondrial cristae and is believed to be involved with the electron transport system.
- Any of the subatomic particles that compose matter and energy, especially one hypothesized or regarded as an irreducible constituent of matter.fundamental particle
- Any of the smallest, discrete entities of which the universe is composed, including the quarks, leptons, and gauge bosons, which are not themselves made up of other particles. Most types of elementary particles have mass, though at least one, the photon, does not. Also called fundamental particle See also composite particle subatomic particle.
The particles that make up the atom. The elementary particles include electrons and a large number of particles, including protons and neutrons, that exist inside the nucleus of atoms. Strictly speaking, the term elementary as applied to most of the particles in the nucleus is inaccurate, for scientists now believe that all the particles except electrons are made of still more elementary particles called quarks.