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

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 Their collective had released only a few songs publicly as of this weekend, but fans got to hear an album's worth of Vernon’s signature falsetto and folktronica dilations combined with Dessner’s guitar and vocals. Erin Richards, Milwaukee Journal Sentinel, "Eaux Claires IV review: Day 1 music," 7 July 2018 Although the patient eventually had her surgery here, the delay resulted in additional uncomfortable dilations in her home state. Nick Manetto, STAT, "Medicaid’s unnecessary barriers delay care for children with complex needs," 1 May 2018 And even after a month of discomfort and blood loss, up to 20 percent of women will still have pregnancy tissue lingering in the uterus and require a dilation and evacuation. Dorothy Novick, STAT, "FDA shouldn’t allow politics to hurt women suffering miscarriage," 22 June 2018 As further research would soon reveal, the primary cause of migraine pain is not dilation of blood vessels in the head, and the primary factor by which triptans help is not by constricting those vessels. R. Allan Purdy, Scientific American, "Can Anything Stop My Migraine?," 1 May 2017

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.

See More

First Known Use of dilation

15th century, in the meaning defined at sense 1

Keep scrolling for more

Learn More about dilation

Statistics for dilation

Last Updated

1 Mar 2019

Look-up Popularity

Time Traveler for dilation

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

See more words from the same century

Keep scrolling for more

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

Comments on dilation

What made you want to look up dilation? Please tell us where you read or heard it (including the quote, if possible).


marked by a state of overwhelming emotion

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Latin Quiz

  • roman forum
  • Which of the following months comes from a Latin word for “ten”?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!