free electron

noun Physics.

an electron that is not attached to an atom or molecule and is free to respond to outside forces.

Origin of free electron

First recorded in 1905–10

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for free electron

free electron

noun

any electron that is not attached to an ion, atom, or molecule and is free to move under the influence of an applied electric or magnetic field

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012