optical fibern. A flexible transparent fiber of extremely pure glass or plastic, generally between 10 and 200 microns in diameter, through which light can be transmitted by successive internal reflections, commonly used in telecommunications. American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.fi?ber op?tics or fi?ber?op?tics, n. the technology of sending computer data, video and voice signals, etc., through laser-generated light carried in bundles of ultrapure, transparent fiber (optical fiber) whose refraction properties allow the light to be transmitted around curves. [1960?65] fi`ber?op?tic, adj. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.optical fiber A flexible transparent fiber, usually made of glass or plastic, through which light can be reflected to transmit images or data from one end to the other. Unlike other communications cables, which are made of metal and transmit data as fluctuating electric currents, optical fibers transmit data as pulses of light. See more at fiber optics.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.