Change or dispersion of the direction and intensity of a wave as it traverses an object or aperture, especially when the size of the object or aperture approximates the wavelength of the wave.
[New Latin diffrāctiō, diffrāctiōn-, from Latin diffrāctus, past participle of diffringere : dis-, apart; see DIS- + frangere, to break; see bhreg- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.