a small particle similar to an electron, but with a positive electric charge

A positron is a small particle similar to an electron, but with a positive electric charge.

an elementary particle of antimatter

A positron is an elementary particle of antimatter.

This anti-electron

This anti-electron is also known as a positron.

An electron travelling backwards in time

An electron travelling backwards in time is what we call a positron.

an antiparticle with a positive charge

The stable leptons are the electron (with a negative charge) and the positron (an antiparticle with a positive charge).

the antimatter counterpart of the electron

Scientists know that every matter particle has an antimatter partner particle with opposite charge; for instance, the antimatter counterpart of an electron is a positron.

a positively charged particle

Well, a positron's a positively charged particle, but a positron isn't a proton.

which is an electron with positive electric charge

For example, the particle conjugated to the electron with the electron's negative electric charge is positron, which is an electron with positive electric charge.

an antimatter counterpart called the positron

The electron has an antimatter counterpart called the positron.

the antiparticle of the electron – a particle with the same mass but opposite charge

The positron is the antiparticle of the electron – a particle with the same mass but opposite charge.

just a different name for anti-electron

Positron is just a different name for anti-electron.

a particle just like an electron

(A positron is a particle like an electron but with a positive charge; a neutrino is a particle with no charge and negligible mass.)

the first discovered particle of antimatter

Positron is the first discovered particle of antimatter; electrons is the antiparticle of an electron.

A positively charged beta particle

A negatively charged beta particle is identical to an electron, while a positively charged beta particle is called a positron.

a particle of antimatter, which we do not observe in daily lives

Positron is a particle of antimatter, which we do not observe in daily lives.