ul·tra·sound (?l?tr?-sound?)n.1. Ultrasonic sound.2. a. The use of ultrasonic waves for diagnostic or therapeutic purposes, specifically to image an internal body structure, monitor a developing fetus, or generate localized deep heat to the tissues.b. An image produced by ultrasound.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.ultrasound (??ltr??sa?nd) n (General Physics) ultrasonic waves at frequencies above the audible range (above about 20 kHz), used in cleaning metallic parts, echo sounding, medical diagnosis and therapy, etcCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ul?tra?sound (??l tr??sa?nd) n. 1. sound with a frequency greater than 20,000 Hz, approximately the upper limit of human hearing. 2. Med. the application of ultrasonic waves to therapy or diagnostics, as in deep-heat treatment of a joint or in ultrasonography. [1920?25] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.ul·tra·sound (?l?tr?-sound?)1. Sound whose wave frequency is too high (over 20,000 hertz) to be heard by humans.2. The medical use of ultrasound waves, especially to produce images of the inside of the body or to observe a developing fetus.ultrasonic (?l?tr?-s?n??k) adjectiveDid You Know? Many people own and use simple ultrasound generators: dog whistles that produce tones that dogs can hear but are too high to be heard by humans. Any sound whose frequency is higher than the upper end of the normal range of human hearing (higher than 20,000 hertz?that is, 20,000 sound waves per second) is called ultrasound. (Sound at frequencies too low to be audible?about 20 hertz or lower?is called infrasound.) The familiar medical ultrasound images (of a fetus in the womb, for example) are made by directing ultrasonic waves into the body, where they bounce off internal organs and other objects and are reflected back to a detector. Ultrasonic waves have very short wavelengths, and so they can create images of very small objects. Ultrasound can also be used to focus large amounts of energy into very small spaces, making it possible, for example, to break up kidney stones without making any surgical incisions.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.ultrasound, ultrasonography – Ultrasounds and ultrasonography work on the principle that sound is reflected at different speeds by tissues or substances of different densities.See also related terms for reflected.Farlex Trivia Dictionary. © 2012 Farlex, Inc. All rights reserved.