dilate
Americanverb (used with object)
-
dilates,
present (3rd person singular)
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dilated,
past participle, past
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dilating
present participle
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to make wider or larger; cause to expand.
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Archaic. to describe or develop at length.
verb (used without object)
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dilates,
present (3rd person singular)
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dilated,
past participle, past
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dilating
present participle
-
to spread out; expand.
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to speak or write at length; expatiate (often followed by on orupon ).
verb
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to expand or cause to expand; make or become wider or larger
the pupil of the eye dilates in the dark
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(intr; often foll by on or upon) to speak or write at length; expand or enlarge
Synonym Usage
See expand.
Other Word Forms
Derived Forms
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dilatabilitynoun
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dilationnoun
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nondilatabilitynoun
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overdilateverb
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redilateverb
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dilatableadjective
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dilatationaladjective
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dilativeadjective
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nondilatableadjective
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self-dilatedadjective
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subdilatedadjective
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undilatableadjective
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undilatedadjective
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undilatingadjective
Inflected Forms
Participles
Conjugated Forms
Present
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dilatesimple
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dilatessimple
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have dilatedperfect
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has dilatedperfect
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am dilatingprogressive
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are dilatingprogressive
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is dilatingprogressive
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have been dilatingperfect progressive
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has been dilatingperfect progressive
Past
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dilatedsimple
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had dilatedperfect
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was dilatingprogressive
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were dilatingprogressive
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had been dilatingperfect progressive
Future
Etymology
Origin of dilate
First recorded in 1350–1400; Middle English dilaten, from Middle French dilater, “to comment at length, enlarge,” from Latin dīlātāre “to spread out, widen,” equivalent to dī- di- 2 + lāt(us) “wide” + -āre infinitive suffix
Explanation
To dilate something is to make it wider. When the light fades, the pupil of your eye will dilate, meaning it looks bigger. The verb dilate comes from the Latin word dilatare, which means “enlarge” or “spread out.” When something stretches, expands, or becomes wider, it is said to dilate. Usually the word dilate is used when the opening of something circular becomes larger, but every so often you might hear someone refer to the need to dilate someone's understanding of quantum physics, global warming, livestock breeding, or any other topic.
Vocabulary lists containing dilate
The Absolutely True Diary of a Part-Time Indian
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Selected Short Stories of Flannery O'Connor
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"The Tragedy of Hamlet," Vocabulary from Act 1
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Atropine eye drops are typically used to dilate the pupil before eye exams.
From The Wall Street Journal ● Dec. 28, 2025
As a result, blood flow to that area increases dramatically as blood vessels dilate, causing pain and swelling.
From National Geographic ● Feb. 21, 2024
Just as the eye's pupils constrict or dilate like a camera's aperture to adjust how much light gets in, the ears too have their own way to regulate hearing.
From Science Daily ● Nov. 22, 2023
Although it is not an ordinary high blood pressure medicine, it can dilate blood vessels.
From Seattle Times ● Nov. 22, 2023
If So-and-so’s blood pressure was high, she should be given hawthorn to stabilize the collagen and dilate the coronary blood vessels.
From "Educated" by Tara Westover
It's a different sort of time and it moves, it dilates.
From Salon ● Feb. 6, 2024
Their study, published Dec. 5 in the journal Cell, focuses on nitric oxide, a compound that dilates blood vessels, improves memory, fights infection and stimulates the release of hormones, among other functions.
From Science Daily ● Dec. 8, 2023
Adenosine is a by-product of energy metabolism, but it also acts as an inhibitory neurotransmitter—a chemical messenger that affects brain cells and dilates blood vessels.
From Scientific American ● Oct. 25, 2023
The drug also dilates the cervix and blocks the effects of progesterone, which is needed to sustain a pregnancy.
From Washington Post ● Aug. 8, 2022
At the edge of the rectangle, a thin slit of light dilates wider.
From "100 Sideways Miles" by Andrew Smith
And if the aorta is dilated a certain amount, patients often undergo an elective surgery to fix it.
From MarketWatch ● Jul. 13, 2026
In a dark room, a doctor pointed to an hourglass shape glowing on the ultrasound screen: There was her amniotic sac, funneling into her dilated cervix, and there was their tiny daughter’s foot, dipping out.
From Salon ● May 27, 2026
About 35 minutes in, Lamphere’s vitals started spiking; her heart rate quickened, she grew hot, her pupils dilated, she began grinding her teeth.
From Slate ● Jan. 30, 2026
“I have been in lunch rooms where women are in labor, dilated, and trying to work until the very last minute because they don’t have enough days.”
From Los Angeles Times ● May 15, 2025
As the tan and white fur grew closer, Ignatius’ eyes dilated, crossed, and closed, and he lay wanly back among his four pillows, hoping that he had some Kleenex in his room.
From "A Confederacy of Dunces" by John Kennedy Toole
Scholars and intellectuals dilating in their little books: None of that matters anymore.
From The Wall Street Journal ● Jan. 15, 2026
Erectile dysfunction drugs, which work by dilating blood vessels to allow more blood to flow through, were first developed to treat high blood pressure.
From Science Daily ● Feb. 7, 2024
The exhaustive format played to President Macron's strengths: his mastery of detail and obvious delight in dilating on every conceivable subject.
From BBC ● Jan. 17, 2024
Some also have trouble with the lining of their small blood vessels not dilating and constricting properly to move blood through, she added.
From Seattle Times ● Aug. 9, 2023
The gray-haired man, his nostrils dilating, appeared to take a fairly deep breath.
From "Nine Stories" by J. D. Salinger
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Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
