Real Dictionary

electron in American English
the lightest elementary particle with an electric charge: it is a lepton with a negative charge of c. 1.602 × 10-19 coulomb and a rest mass of c. 9.109 × 10-31 kg (c. 0.511 MeV/c2), which is c. 1⁄1836 of the mass of a proton: ordinarily an atom has the sa
noun: an elementary particle that is a fundamental constituent of matter, having a negative charge of 1.602 × 10−19 coulombs, a mass of 9.108 × 10−31 kilograms, and spin of 1⁄2, and existing independently or as the component outside the nucleus of an atom

electron in British English
noun: a stable elementary particle present in all atoms, orbiting the nucleus in numbers equal to the atomic number of the element in the neutral atom; a lepton with a negative charge of 1.602 176 462 × 10–19 coulomb, a rest mass of 9.109 381 88 × 10–31 kilogra

electron in Electrical Engineering
noun: An electron is an elementary particle that has a negative charge and is a constituent of all atoms.