di·​la·​tion | \ dī-ˈlā-shən How to pronounce dilation (audio) \

Definition of dilation

1 : the act or action of dilating : the state of being dilated : expansion, dilatation
2 : the action of stretching or enlarging an organ or part of the body

Examples of dilation in a Sentence

Recent Examples on the Web

The dilation and evacuation procedure accounted for 27, or 0.35 percent, of the 7,778 abortions performed in Indiana during 2017, according to an Indiana State Department of Health report. Tom Davies, Post-Tribune, "Judge questions reasons for Indiana abortion procedure ban," 3 June 2019 Emoticons and words are poor substitutes for the body itself, though: Through gaze direction, expressions, tone of voice, posture, pupil dilation and gestures, the body is much better than language at communicating a wide range of meanings. Frans De Waal, Discover Magazine, "Cheerful Chimps: Are Animals Really Happy When They Smile?," 31 May 2019 Then there’s the theory that air pressure fluctuations can prompt changes in your body like dilation of your blood vessels, which can in turn spark migraines, Dr. Weber explains. Korin Miller, SELF, "Is It True That the Weather Can Cause a Migraine?," 3 Aug. 2018 Indiana Solicitor General Thomas Fisher started his arguments Monday with a description of how the dilation and evacuation procedure is performed on the fetus, but Barker quickly interrupted him. Tom Davies, Post-Tribune, "Judge questions reasons for Indiana abortion procedure ban," 3 June 2019 These exams include a number of procedures to assess both your eyesight and ocular health, including pupil dilation to see the optic nerve and retina and a thorough look at the front of your eye to look for things like cataracts or cornea scratches. Carolyn L. Todd, SELF, "Exactly How Often You Really Need to See Different Kinds of Doctors," 17 Jan. 2019 Laukkanen hypothesizes that improved arterial flexibility and dilation reduces the amount of force that moving blood exerts on the blood vessel walls. SELF, "Does the Steam Room at the Gym Actually Do Anything?," 4 Jan. 2019 In other words, the drone would be able to detect barometers of a person's energy such as blood pressure, pupil dilation, and facial expressions, and then give them a caffeinated boost as a result. David Grossman, Popular Mechanics, "IBM Files Patent For a Coffee Delivery Drone," 24 Aug. 2018 In June 2017, Texas Governor Gregg Abbott signed a law banning the most common method of ending a pregnancy in the second trimester, known as dilation and evacuation, during which the fetus is removed from the uterus. Kayla Webley Adler, Marie Claire, "If Brett Kavanaugh Is Confirmed, These 5 Scary Things Could Easily Happen," 31 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'dilation.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of dilation

15th century, in the meaning defined at sense 1

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Last Updated

21 Jun 2019

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The first known use of dilation was in the 15th century

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More Definitions for dilation


di·​la·​tion | \ dī-ˈlā-shən How to pronounce dilation (audio) \

Medical Definition of dilation

1 : the state of being dilated : dilatation
2 : the action of stretching or enlarging an organ or part of the body cervical dilation dilation of the pupil with atropine

More from Merriam-Webster on dilation

Rhyming Dictionary: Words that rhyme with dilation

Nglish: Translation of dilation for Spanish Speakers

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