electromagnetic spectrumelectromagnetic spectrum frequencies in hertzA. gamma raysB. x-raysC. ultraviolet raysD. visible lightE. infrared raysF. microwavesG. radio waveselectromagnetic spectrumn. The entire range of electromagnetic radiation, which includes, in order of increasing frequency and decreasing wavelength, radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, x-rays, and gamma rays.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.electromagnetic spectrum n (General Physics) the complete range of electromagnetic radiation from the longest radio waves (wavelength 105 metres) to the shortest gamma radiation (wavelength 10?13 metre) Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014elec?tromagnet?ic spec?trum n. the entire continuous spectrum of all forms of electromagnetic radiation, from gamma rays to long radio waves. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.electromagnetic spectrumThe electromagnetic spectrum can be measured in frequencies or in wavelengths. This diagram measures wavelengths in meters, ranging from the longest wavelengths (radio waves) to the shortest (gamma rays). Visible light, which is a band of colors from red to violet, is the only portion of the spectrum that can be seen by the human eye.electromagnetic spectrum The entire range of electromagnetic radiation. At one end of the spectrum are gamma rays, which have the shortest wavelengths and high frequencies. At the other end are radio waves, which have the longest wavelengths and low frequencies. Visible light, with intermediate wavelengths and frequencies, is near the center of the spectrum.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.electromagnetic spectrumThe range of frequencies of electromagnetic radiation from zero to infinity. It is divided into 26 alphabetically designated bands. See also electronic warfare.Dictionary of Military and Associated Terms. US Department of Defense 2005.