ultrasound

n. sound waves with frequencies higher than 20000 megahertz (above the range of human hearing); use of ultrasonic waves for medical imaging and treatment

Ultrasound is a cyclic sound pressure with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz).
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Ultrasound /ul·tra·sound/ 1. sound waves of a frequency greater than 20,000 Hz. 2. ultrasonography. ul·tra·sound n. Abbr. U/S 1. Ultrasonic sound. 2. [more]Ultrasound - Community and Resources

Noun
1. very high frequency sound; used in ultrasonography
(hypernym) sound
2. using the reflections of high-frequency sound waves to construct an image of a body organ (a sonogram); commonly used to observe fetal growth or study bodily organs
(synonym) sonography, ultrasonography
(hypernym) imaging, tomography

A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echo patterns are shown on the screen of an ultrasound machine, forming a picture of body tissues called a sonogram. Also called ultrasonography.