What does antimatter mean?
Antimatter is matter composed of antiparticles — subatomic counterparts of ordinary particles that carry opposite charges and certain reversed quantum properties. The positron, discovered by Carl Anderson in 1932, mirrors the electron; the antiproton mirrors the proton. Antimatter is not hypothetical: it is routinely produced in particle accelerators, occurs naturally in cosmic-ray showers and even in some radioactive decay, and has been briefly trapped in tiny amounts at facilities such as CERN. Its most striking property is annihilation — when a particle meets its antiparticle, both are converted entirely into energy, a process far more efficient than any chemical or nuclear reaction. This makes antimatter a staple of speculative propulsion systems and fiction, while also posing one of physics' deepest puzzles: why the Big Bang left a universe dominated by matter rather than equal parts of both. In everyday language, 'antimatter' evokes cutting-edge science and enormous latent power.
nounMatter composed of antiparticles, which have the same mass as particles of ordinary matter but opposite charges and quantum properties. When antimatter meets matter, both are annihilated, releasing energy.
- Matter composed of antiparticles (e.g. positrons, antiprotons) with properties mirroring those of ordinary matter but of opposite charge or quantum number.
"Physicists at CERN managed to trap a small quantity of antimatter for over sixteen minutes."
"When an electron meets its antimatter counterpart, the positron, both particles vanish in a burst of gamma rays."
"In Dan Brown's novel Angels & Demons, a stolen vial of antimatter threatens to destroy Vatican City."
Antimatter is uncountable and has no plural form; refer to quantities using phrases like 'a trace amount of antimatter'.
"The detector registered a faint signal from annihilating antimatter."
A single gram of antimatter annihilating with matter would release roughly the energy of a nuclear bomb — yet making just that gram would cost trillions of dollars and take millions of years at current production rates.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of antimatter
The term 'antimatter' combines the Greek-derived prefix 'anti-', meaning 'against' or 'opposite', with 'matter', from Latin 'materia', meaning substance or material. It was coined in the twentieth century following Paul Dirac's 1928 theoretical prediction of the positron and its subsequent experimental discovery, when physicists needed a name for matter built from these mirror-image particles. The prefix 'anti-' appears in many scientific words denoting opposition, such as 'antibody' and 'antineutron'.
How antimatter is actually used
Antimatter is an uncountable noun used almost exclusively in scientific, technical, and science-fiction contexts. It takes no plural form; quantities are expressed as 'an amount of antimatter' rather than 'antimatters'. The word carries connotations of futuristic technology and immense destructive potential in popular culture.
Easily confused with antimatter
Dark matter is hypothetical invisible matter inferred from its gravitational effects on galaxies; antimatter is real matter made of antiparticles that annihilates on contact with ordinary matter.
Matter is the ordinary substance of the universe made of particles such as protons and electrons, whereas antimatter is composed of their oppositely charged counterparts.