dilate
Americanverb (used with object)
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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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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
Related Words
See expand.
Other Word Forms
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.
Atropine eye drops are typically used to dilate the pupil before eye exams.
From The Wall Street Journal • Dec. 28, 2025
A typical remedy is to stretch or dilate the urethra, a minimally invasive procedure that is often performed with general anesthesia, Dr. Lepor said.
From New York Times • Feb. 12, 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
At regular concentrations of about 1 percent, atropine is used to dilate the pupil for eye exams.
From National Geographic • Nov. 1, 2023
It made her skin flush and her eyes dilate, and some part of her marveled at the focus of the energy that ran through her.
From "Huntress" by Malinda Lo
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
