electron

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A stable subatomic particle in the lepton family having a rest mass of 9.1066 × 10^-28 grams and a unit negative electric charge of approximately 1.602 × 10^-19 coulombs. See Table at subatomic particle.

Century Dictionary and Cyclopedia

1. n. Same as electrum.
2. n. In phys. chew., the definite charge of electricity which is associated with a univalent ion. Sometimes called an atom of electricity. See electricity.
3. n. According to a recent hypothesis, a minute particle detached from an atom of a gas by certain agencies, as when the gas is carrying an electric current. The electron has a mass of something like one thousandth of the mass of an atom of hydrogen, and possesses (or consists of) a negative electric charge equal to that of the negative univalent ion of electrolytic conduction. In a gas at very low pressures, the electron constitutes the negative ion of gaseous conduction, while the atom from which the electron has been detached constitutes the positive ion. In gases at greater pressures, electrically neutral molecules become attached to the electron and to the atom from which the electron has been detached, and these complex systems constitute the ions of gaseous conduction at atmospheric pressure. In liquid electrolytes, according to this theory, an atom or radical from which one, two, or three electrons have been detached is a positive univalent, bivalent, or trivalent ion. An atom or radical to which one or more electrons have been attached constitutes a negative ion of the corresponding valence. In metallic conductors the electrons pass from an atom to an adjacent atom without producing electrolysis or chemical decomposition. The experimental basis of the hypothesis has been chiefly discovered by J. J. Thomson, with the aid of some of his pupils.

Wiktionary

1. n. physics The subatomic particle having a negative charge and orbiting the nucleus; the flow of electrons in a conductor constitutes electricity.
2. n. chemistry, obsolete Alloys of magnesium and other metals, like aluminum or zinc, that were manufactured by the German company Chemische Fabrik Griesheim-Elektron.

GNU Webster's 1913

1. n. archaic Amber; also, the alloy of gold and silver, called electrum.
2. n. (Physics & Chem.) one of the fundamental subatomic particles, having a negative charge and about one thousandth the mass of a hydrogen atom. The electron carries (or is) a natural unit of negative electricity, equal to 3.4 x 10-10 electrostatic units, and is classed by physicists as a lepton. Its mass is practically constant at the lesser speeds, but increases due to relativistic effects as the velocity approaches that of light. Electrons are all of one kind, so far as is known. Thus far, no structure has been detected within an electron, and it is probably one of the ultimate composite constituents of all matter. An atom or group of atoms from which an electron has been detached has a positive charge and is called a cation. Electrons are projected from the cathode of vacuum tubes (including television picture tubes) as cathode rays and from radioactive substances as the beta rays. Previously also referred to as corpuscle, an obsolete term. The motion of electrons through metallic conductors is observed as an electric current. A particle identical to the electron in mass and most other respects, but having a positive instead of a negative charge, is called a positron, or antielectron

WordNet 3.0

1. n. an elementary particle with negative charge