dilated; dilating

intransitive verb

: to become enlarged or widened
Kim's eyes dilated while the outdoor stadium rocked in celebration.Ralph Wiley
… arterioles continually dilate and constrict.Janet Raloff
also : to display or become affected by expansion or widening of a body part
The expectant mother was dilating slowly. [=The expectant mother's cervix was dilating slowly.]
: to become expanded in extent
Understandably, a tendency to philosophize dilated with old age.Anthony Powell
Time dilates when you mentally hop continents.Bret Wallach
: to comment at length : discourse
usually used with on or upon
It's no small irony that a man who made a career out of dilating on failure should have ended up a success.James Atlas
He dwells and dilates upon every highlight and lowlight …The New Yorker

transitive verb

: to enlarge, widen, or cause to expand
Nitric oxide is a potent vasodilator that increases blood flow by dilating blood vessels.Ruth MacPete
Inhalers, the standard treatment for asthma, relieve wheezing by delivering an agent that dilates the bronchioles …Tony Dajer
Cocaine … increases the heart rate, raises the blood pressure and, in large doses, increases the body temperature and dilates the pupils of the eyes.Craif Van Dyke and Robert Byck
: to expand in extent
dilate our cultural knowledge
Like millions of other urban youths in the 1960s, Tian got a chance to dilate his horizons when he was sent into the countryside during the Cultural Revolution to learn from the peasantry.Lawrence Chua
archaic : to describe or set forth at length or in detail
Do me the favor to dilate at full / What hath befallen of them …William Shakespeare
dilatable adjective
dī-ˈlā-tər How to pronounce dilate (audio)
Choose the Right Synonym for dilate

expand, amplify, swell, distend, inflate, dilate mean to increase in size or volume.

expand may apply regardless of the manner of increase (such as growth, unfolding, addition of parts).

a business that expands every year

amplify implies the extension or enlargement of something inadequate.

amplify the statement with details

swell implies gradual expansion beyond a thing's original or normal limits.

the bureaucracy swelled to unmanageable proportions

distend implies outward extension caused by pressure from within.

a distended abdomen

inflate implies expanding by introduction of air or something insubstantial and suggests a vulnerability to sudden collapse.

an inflated ego

dilate applies especially to expansion of circumference.

dilated pupils

Examples of dilate in a Sentence

The drug causes the blood vessels to dilate. During labor, a woman's cervix will dilate to about 10 centimeters. The drug dilates the blood vessels.
Recent Examples on the Web Also, young vessels are more compliant, dilating to increase diameter when there is a need for more blood flow, but this ability also declines with age. Bryant Stamford, The Courier-Journal, 16 May 2024 As a result of the study, the blood vessels’ ability to dilate for the participants in the angry group was significantly reduced in comparison to the control group. Charna Flam, Peoplemag, 1 May 2024 The second drug, misoprostol, taken 24 to 48 hours later, causes the uterus to contract and dilates the cervix, which will expel the embryo. Alexandra Hutzler, ABC News, 26 Mar. 2024 The supplement contains icariin, a compound that stimulates the release of nitric oxide, which dilates blood vessels and promotes circulation. Amber Smith, Discover Magazine, 24 Dec. 2023 Dynamic exercise increases the volume of blood pumping through the heart and can cause the heart to become enlarged, or dilated, over time. William Cornwell, The Conversation, 21 Feb. 2024 Alcohol dilates the blood vessels, which can lead to a pounding headache. Delaney Nothaft, USA TODAY, 19 Jan. 2024 The exhibition spotlights a series of 10 bas-relief paintings (one of which has been loaned to the Aldrich) charting the cervix dilating from 1 cm to 10 cm, the kinds of measurements tracked during a vaginal birth. Stephanie Sporn, Vogue, 8 Feb. 2024 Maybe you were attracted to this person, and your eyes dilated, your pulse went up. David Marchese Photograph By Mamadi Doumbouya, New York Times, 2 Feb. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'dilate.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English, from Middle French dilater, from Latin dilatare, literally, to spread wide, from dis- + latus wide — more at latitude

First Known Use

14th century, in the meaning defined at transitive sense 2

Time Traveler
The first known use of dilate was in the 14th century

Dictionary Entries Near dilate

Cite this Entry

“Dilate.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/dilate. Accessed 23 May. 2024.

Kids Definition


dilated; dilating
: to make or grow larger or wider
lungs dilated with air

Medical Definition


di·​late dī-ˈlāt How to pronounce dilate (audio) ˈdī-ˌ How to pronounce dilate (audio)
dilated; dilating

transitive verb

: to enlarge, widen, or cause to expand
dilate his pupils with atropine
the drug dilates peripheral arteries

intransitive verb

: to become enlarged, expanded, or widened
the cervix was dilating
the pupils dilated

More from Merriam-Webster on dilate

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