define
Americanverb (used with object)
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to state or set forth the meaning of (a word, phrase, etc.).
They disagreed on how to define “liberal.”
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to explain or identify the nature or essential qualities of; describe.
to define judicial functions.
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to fix or lay down clearly and definitely; specify distinctly.
to define one's responsibilities.
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to determine or fix the boundaries or extent of.
to define property with stakes.
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to make clear the outline or form of.
The roof was boldly defined against the sky.
verb (used without object)
verb
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to state precisely the meaning of (words, terms, etc)
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to describe the nature, properties, or essential qualities of
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to determine the boundary or extent of
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(often passive) to delineate the form or outline of
the shape of the tree was clearly defined by the light behind it
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to fix with precision; specify
Other Word Forms
Derived Forms
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definabilitynoun
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definementnoun
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definernoun
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nondefinabilitynoun
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nondefinernoun
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misdefineverb (used with object)
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predefineverb (used with object)
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redefineverb (used with object)
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definableadjective
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nondefinableadjective
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nondefinedadjective
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self-definedadjective
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semidefinedadjective
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undefinableadjective
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definablyadverb
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nondefinablyadverb
Inflected Forms
Participles
Conjugated Forms
Present
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definesimple
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definessimple
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have definedperfect
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has definedperfect
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am definingprogressive
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are definingprogressive
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is definingprogressive
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have been definingperfect progressive
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has been definingperfect progressive
Past
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definedsimple
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had definedperfect
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was definingprogressive
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were definingprogressive
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had been definingperfect progressive
Future
Etymology
Origin of define
First recorded in 1325–75; Middle English def(f)inen, from Anglo-French, Old French definer “to put an end to,” from Latin dēfīnīre ”to limit, define,“ equivalent to dē- “from, away from, out of” + fīnīre “to end”; see origin at de-, finish
Explanation
If you can't define a word, turn to the dictionary. That's always the best way to learn the definition. Likewise, anything you can describe completely is something you can define. The early French and Latin roots of the verb mean something closer to "to limit" or "to create a boundary," but this is really what we do when we define something: we limit its meaning to something specific. So when you're thinking about the word define, remember that you're looking to create a boundary of meaning around it, whether you're specifying the meaning of a word or a larger concept. To define a word such as astronomy is to define both the word and the realm of science that it's concerned with.
Vocabulary lists containing define
The Language of Standardized Tests, List 1
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Jim Burke's Academic Vocabulary List
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The ACT: The Language of the Test, List 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:
"How we define genetic diversity and how we actually measure it is shaped largely by the technology of the day."
From Science Daily ● Jul. 26, 2026
In 1867, an 8-year-old girl named Elizabeth Turner became the epicenter of a legal battle that would help define what freedom really meant after the Civil War.
From Slate ● Jul. 25, 2026
It is difficult to clearly define Rogers by a fixed position.
From BBC ● Jul. 24, 2026
Because UC and CSU share the course requirements, they effectively define the high school course track for college-bound Californians.
From Los Angeles Times ● Jul. 23, 2026
The Harvard men asked the believers to define the spirit manifestations.
From "American Spirits" by Barb Rosenstock
It defines how predictably and agreeably a car will swivel its hips, under braking and throttle, without spinning out.
From The Wall Street Journal ● Jul. 25, 2026
Still, the two retain a lifelong bond that, while reflecting the reality of the world around them, all but defines Best Friends Forever.
From Los Angeles Times ● Jul. 15, 2026
He may have been dissuaded from imposing a toll, but this is the way he thinks, and this is how he defines U.S. interests.
From Slate ● Jul. 15, 2026
The concept is illustrated by the Carnot cycle, an idealized model that defines the maximum theoretical efficiency of a heat engine by carefully regulating the movement of heat between hot and cold regions.
From Science Daily ● Jul. 11, 2026
The river marks the Guatemalan border, just as the Rio Grande defines the Mexican border to the north.
From "Enrique's Journey" by Sonia Nazario
"Being a digital nomad is not defined by nationality. Our community includes members from many countries, including Indonesia."
From BBC ● Jul. 27, 2026
“State laws offer varying definitions that prosecutors have largely accepted, and courts have increasingly defined the category, usually functionally.”
From The Wall Street Journal ● Jul. 27, 2026
What do you think of that approach versus having a more defined plan?
From MarketWatch ● Jul. 27, 2026
Those items are reminders of the work ethic, drive and connection to family that defined Kent’s trek from Huntington Beach to the National Baseball Hall of Fame in Cooperstown, N.Y.
From Los Angeles Times ● Jul. 26, 2026
Instead, tuning itself is now defined in terms of equal-temperament, with tunings and intervals measured in cents.
From "Understanding Basic Music Theory" by Catherine Schmidt-Jones and Russel Jones
The defining question for AI in this era won’t be who tops the leader board for usage.
From The Wall Street Journal ● Jul. 27, 2026
Actors, writers, production staff and movie fans are still resistant to the overuse of AI and defining when and where it is acceptable, so studios are treading lightly, said AI film studio CEO Mooser.
From Los Angeles Times ● Jul. 26, 2026
But creating social cohesion where it is lacking, is surely a defining mission of Burnham's premiership.
From BBC ● Jul. 20, 2026
“The defining feature of this home is its positioning. It captures breathtaking jetliner and mountain views from almost every angle. It’s an absolute standout offering in a premier location.”
From MarketWatch ● Jul. 17, 2026
What excited her about her achievement was its design, the pure geometry and the defining uncertainty which reflected, she thought, a modern sensibility.
From "Atonement" by Ian McEwan
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.