di·​late | \ˈdī-ˌlāt, dī-ˈ \
dilated; dilating

Definition of dilate 

transitive verb

1 archaic : to describe or set forth at length or in detail dilate at full what hath befallen of them— Shakespeare

2 : to enlarge or expand in bulk or extent : distend, widen dilate our cultural knowledge … long after Italian women used drops of belladonna to artificially dilate their pupils.— Michael H. Robinson

intransitive verb

1 : to comment at length : discourse usually used with on or upon dilating upon themes of love and death

2 : to become wide : swell the pupil of the eye dilates and contracts

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Other Words from dilate

dilatability \ (ˌ)dī-​ˌlā-​tə-​ˈbi-​lə-​tē \ noun
dilatable \ dī-​ˈlā-​tə-​bəl , ˈdī-​ˌ \ adjective
dilator \ dī-​ˈlā-​tər , ˈdī-​ˌ \ noun

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.
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Recent Examples on the Web

The state requires across-the-board EKGs, dilated eye exams and a brain CT or MRI scan within five years of a fight. Drew Hill, The Courier-Journal, "At least 6 MMA fighters have died while in the ring or shortly after," 21 June 2018 The thinking at the time was that loss of serotonin caused blood vessels to lose tone and dilate, bringing on migraine pain. R. Allan Purdy, Scientific American, "Can Anything Stop My Migraine?," 1 May 2017 Also, sometimes because of environmental changes, like a lower amount of light , a venomous snake’s eyes can dilate, making them round. Shelia Poole, ajc, "7 most common myths about snakes," 5 June 2018 The thinking is that activity in certain nerve cells makes blood vessels in your brain dilate and also causes a release of inflammatory substances like prostaglandins, which can create pain. Korin Miller, SELF, "9 Health Issues That Can Cause Sensitivity to Light," 5 June 2018 My partner had started to dilate at 29 weeks and our babies were born at 36 weeks. Amber Leventry, Longreads, "Making Peace with Selective Reduction," 29 June 2018 The parents of the other child, Damian, discovered something was wrong with their son's left eye when the pupil became dilated and stayed that way. Daniel Chang, miamiherald, "'They killed my kid.' Parents sue renowned doctor, hospital after children die of cancer | Miami Herald," 21 May 2018 Applying heat during this process can dilate your blood vessels too quickly, causing tears and minor bleeding at the injury site. Michael Yang, Philly.com, "Q&A: Should I use ice or heat to treat my sports injury?," 1 June 2018 These chemicals dilate blood vessels, which can lower blood pressure and increase oxygen-rich blood flow to the brain and muscles. Meghan Overdeep, Southern Living, "Why You Should Be Eating More Beets," 26 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'dilate.' 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 dilate

14th century, in the meaning defined at transitive sense 1

History and Etymology for dilate

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

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Time Traveler for dilate

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

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More Definitions for dilate



English Language Learners Definition of dilate

: to become larger or wider


di·​late | \dī-ˈlāt \
dilated; dilating

Kids Definition of dilate

: to make or grow larger or wider Her pupils dilated in the dark.


di·​late | \dī-ˈlāt, ˈdī-ˌ \
dilated; dilating

Medical Definition of dilate 

transitive verb

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

intransitive verb

: to become expanded or swollen the cervix was dilating the pupils dilated

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More from Merriam-Webster on dilate

Spanish Central: Translation of dilate

Nglish: Translation of dilate for Spanish Speakers

Britannica English: Translation of dilate for Arabic Speakers

Comments on dilate

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by force of circumstances

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