ultrasound

American  

[uhl-truh-sound] / ˈʌl trəˌsaʊnd /

noun

1. Physics. sound with a frequency greater than 20,000 Hz, approximately the upper limit of human hearing.

2. Medicine/Medical. the application of ultrasonic waves to therapy or diagnostics, as in deep-heat treatment of a joint or imaging of internal structures.

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ultrasound British  

/ ˈʌltrəˌsaʊnd /

noun

1. ultrasonic waves at frequencies above the audible range (above about 20 kHz), used in cleaning metallic parts, echo sounding, medical diagnosis and therapy, etc

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ultrasound Scientific  

/ ŭl′trə-sound′ /

1. Sound whose frequency is above the upper limit of the range of human hearing (approximately 20 kilohertz).

2. See ultrasonography

3. An image produced by ultrasonography.

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ultrasound Cultural  

1. A method of diagnosing illness and viewing internal body structures in which sound waves of high frequency are bounced off internal organs and tissues from outside the body. The technique measures different amounts of resistance the body parts offer to the sound waves, and then uses the data to produce a “picture” of the structures. Ultrasound is often used to obtain an image of the developing fetus in pregnant women; the image can confirm the presence of twins or triplets and can be used to diagnose some abnormalities.

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Closer Look

Many people use simple ultrasound generators. Dog whistles, for example, produce tones that dogs can hear but that are too high to be heard by humans. Sound whose frequency is higher than the upper end of the normal range of human hearing (higher than about 20,000 hertz) is called ultrasound. (Sound at frequencies too low to be audible—about 20 hertz or lower—is called infrasound.) Medical ultrasound images, such as those of a fetus in the womb, 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. Ultrasound imaging, also known as ultrasonography, is particularly useful in conditions such as pregnancy, when x-rays can be harmful. Because ultrasonic waves have very short wavelengths, they interact with very small objects and thus provide images with high resolution. For this reason ultrasound is also used in some microscopes. Ultrasound can also be used to focus large amounts of energy into very small spaces by aiming multiple ultrasonic beams in such a way that the waves are in phase at one precise location, making it possible, for example, to break up kidney stones without surgical incision and without disturbing surrounding tissue. Ultrasound's industrial uses include measuring thicknesses of materials, testing for structural defects, welding, and aquatic sonar.

Discover More

When an image of the inside of the body is needed, ultrasound is often considered a safer alternative to x-rays. Like x-rays, ultrasound involves exposure of the body to a form of radiation; unlike x-rays, ultrasound has not been shown to be carcinogenic.

Etymology

Origin of ultrasound

First recorded in 1920–25; ultra- + sound ¹

Compare meaning

How does ultrasound compare to similar and commonly confused words? Explore the most common comparisons:

• ultrasonic vs. ultrasound

Explanation

The noun ultrasound is a medical term for a scan that allows doctors to easily and safely see inside a patient's body. An ultrasound uses inaudible sound waves to create a picture of a person's internal organs, muscles, bones, and other body parts. The type of ultrasound that's most familiar to non-medical professionals is the kind that allows a doctor or technician to see a fetus from the outside of a pregnant woman's stomach. The person who performs an ultrasound is called a sonographer or a radiologist.

Example Sentences

Ultrasound is non-invasive, does not use ionizing radiation and has no known harmful effects.

From BBC • Dec. 3, 2025

Ultrasound allows experts to look at the kidneys to determine the severity of the disease.

From Los Angeles Times • Aug. 19, 2025

She said she did not know why she wasn’t but pointed ProPublica to the Society of Radiologists in Ultrasound criteria, which is hanging on the clinic’s wall and is used to teach residents.

From Salon • Jul. 2, 2025

"Ultrasound waves can penetrate more than 100 times deeper than light while still spatially confined, so we can reach tissues, bones and organs with high spatial precision that haven't been reachable with light-based printing methods."

From Science Daily • Dec. 7, 2023

Ultrasound machines bounce acoustic waves off body tissues to create an image, and MRI involves injecting a dye that helps visualize tissues and blood vessels in greater detail.

From Scientific American • Jun. 2, 2023