Definition of "electron" []

• 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. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The proton and the neutron have a diameter of 10-15m (a femtometre or a millionth of a millionth of a millimetre) and the electron is at least 1,000 times smaller."
• "Its resolving power could be considered theoretically unlimited, since the electron is a pointlike particle, However, according to quantum mechanics, every particle has wave characteristics which introduce an uncertainty into the determination of its position."
• "It had been known since long that the electron is a small magnet."