Matter in which the core particles (neutrons, protons, electrons) are replaced by the corresponding antiparticles (antineutrons, antiprotons, positrons).

also anti-matter, 1953, from anti- + matter (n.).

Click for a picture Pair production and pair annihilation of hydrogen and antihydrogen particles (Source: Riken Research: http://www.rikenresearch.riken.jp/eng/frontline/5444) A large accumulation of [..]

Matter consisting of particles with charges opposite that of ordinary matter.  In antimatter, protons have a negative charge while electrons have a positive charge.

Matter made up of elementary particles whose masses are identical to their normal-matter counterparts but whose other properties, such as electric charge, are reversed. The positron is the antimatter [..]

Matter made up of elementary particles whose masses are identical to their normal-matter counterparts but whose other properties, such as electric charge, are reversed. The positron is the antimatter [..]

The 'opposite' to ordinary matter. For every particle of ordinary matter there is an almost identical antiparticle of antimatter: protons and antiprotons; electrons and positrons... the particle's mass is exactly the same as its antiparticle's mass, but their electrical charges - and other fundamental properties - are opposite. [..]

A substance composed of antiparticles.

Material made from antifermions. We define the fermions that are common in our universe as matter and their antiparticles as antimatter. In the particle theory there is no a priori distinction between [..]

All particles of ordinary matter (electrons, protons, neutrons) have anti-matter partners that appear identical in all respects (e.g. mass, spin) except that they have the opposite electric charge. We believe that in the Big Bang equal quantities of matter and antimatter were created. The fact that the universe now contains matter and not anti-matt [..]

Matter composed of the antiparticles ofnormal matter.

(physics) Matter that is composed of the antiparticles of those that constitute normal matter.

(n) matter consisting of elementary particles that are the antiparticles of those making up normal substances

(n.) A type of matter in which each particle (antiproton, antineutron, etc.) is opposite in charge and certain other properties to a corresponding particle (proton, neutron, etc.) of the same mass of [..]

When an antimatter particle meets with a matter particle they annihilate each other! Both particles disappear and two gamma rays are produced instead. Antimatter does not get very far through matter b [..]

the opposite of regular matter. For every particle of ordinary matter there is an almost identical antiparticle of antimatter.

is matter composed of anti-particles: antiprotons, antineutrons, and positrons. Hypothetically a type of matter identical to physical matter except that the atoms are made of: anti-electrons, anti-pro [..]

Matter made up of elementary particles whose masses are identical to their normal-matter counterparts but whose other properties, such as electric charge, are reversed. The positron is the antimatter counterpart of an electron, with a positive charge instead of a negative charge. When an antimatter particle collides with its normal-matter counterpa [..]