know
1 Americanverb (used with object)
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to perceive or understand as fact or truth; to apprehend clearly and with certainty.
I know the situation fully.
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to have established or fixed in the mind or memory.
to know a poem by heart; Do you know the way to the park from here?
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to be cognizant or aware of.
I know it.
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be acquainted with (a thing, place, person, etc.), as by sight, experience, or report.
to know the mayor.
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to understand from experience or attainment (usually followed by how before an infinitive).
to know how to make gingerbread.
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to be able to distinguish, as one from another.
to know right from wrong.
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Archaic. to have sexual intercourse with.
verb (used without object)
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to have knowledge or clear and certain perception, as of fact or truth.
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to be cognizant or aware, as of some fact, circumstance, or occurrence; have information, as about something.
noun
idioms
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know the ropes, to understand or be familiar with the particulars of a subject or business.
He knew the ropes better than anyone else in politics.
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in the know, possessing inside, secret, or special information.
noun
verb
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(also intr; may take a clause as object) to be or feel certain of the truth or accuracy of (a fact, etc)
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to be acquainted or familiar with
she's known him five years
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to have a familiarity or grasp of, as through study or experience
he knows French
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(also intr; may take a clause as object) to understand, be aware of, or perceive (facts, etc)
he knows the answer now
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(foll by how) to be sure or aware of (how to be or do something)
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to experience, esp deeply
to know poverty
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to be intelligent, informed, or sensible enough (to do something)
she knew not to go home yet
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(may take a clause as object) to be able to distinguish or discriminate
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archaic to have sexual intercourse with
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I have an idea
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to know how one thing or things in general work
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informal a parenthetical filler phrase used to make a pause in speaking or add slight emphasis to a statement
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things are uncertain
noun
Usage
What are other ways to say know? To know something is to perceive or understand it as fact or truth. When should you use this verb over understand or comprehend? Find out on Thesaurus.com.
Other Word Forms
Derived Forms
Inflected Forms
Participles
Conjugated Forms
Present
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knowsimple
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knowssimple
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have knownperfect
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has knownperfect
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am knowingprogressive
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are knowingprogressive
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is knowingprogressive
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have been knowingperfect progressive
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has been knowingperfect progressive
Past
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knewsimple
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had knownperfect
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was knowingprogressive
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were knowingprogressive
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had been knowingperfect progressive
Future
Etymology
Origin of know
First recorded before 900; Middle English knowen, knawen, Old English gecnāwan; cognate with Old High German -cnāhan, Old Norse knā “to know how, be able to”; akin to Greek gignṓskein, Latin (g)nōscere, Sanskrit jñātá “known”; see also can 1, gnostic
Explanation
To know something means to have a piece of information or a certain understanding of something. If someone tells you their phone number and you remember it, you know. There's a reason you can find the word know in the word knowledge — to know is to have knowledge about something, to be familiar with an idea, or to recognize someone. If you're "in the know," you have information that is only known to a select group of people. But be careful — to know someone in the Biblical sense means that you're having sexual relations with them.
Vocabulary lists containing know
Words from "Miss Alaineus, A Vocabulary Disaster" by Debra Frasier
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Spelling Practice 1, Unit 3
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Spelling Practice, Unit 8
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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:
You don’t have to stick to Apple-branded cables and bricks, but you should know how to distinguish a good deal from a potential hazard.
From The Wall Street Journal ● Jul. 13, 2026
Graham replied: “Well, OK, from my point of view, if you know anything about me, it’d be odd not to do this.”
From Slate ● Jul. 13, 2026
If you want to know who he is, look only at what he shares in his creative output.
From Los Angeles Times ● Jul. 13, 2026
"You know my thoughts on Harry, my affection for him as a player, person and leader," said McCullum.
From BBC ● Jul. 13, 2026
Each group is given a secret code, though they don’t know what it means or what it’s for.
From "At Last She Stood" by Erin Entrada Kelly
A World Cup prediction: As Jeremy Stahl has watched this tournament progress, he’s become convinced that he knows how it will end.
From Slate ● Jul. 13, 2026
He knows politicians use him "like tissue paper", but is still grateful for the cash.
From Barron's ● Jul. 13, 2026
Noskova’s a new darling, and on the men’s side, it’s Sinner versus Pray for Carlos or who the heck knows.
From The Wall Street Journal ● Jul. 12, 2026
Who knows what might have happened after that?
From BBC ● Jul. 12, 2026
He knows that I know it, from the way that our eyes meet in that dark train yard.
From "The Brightwood Code" by Monica Hesse
This was nonsense, and Graham knew it; oil played little role in anything concerning Syria at the time.
From Slate ● Jul. 13, 2026
“It was cool to see someone I knew get picked that high,” Bremner said.
From Los Angeles Times ● Jul. 12, 2026
“I knew that if I stuck in computer science, it might just end up being a minimum wage job by the time I graduated,” said Allen, 24.
From The Wall Street Journal ● Jul. 12, 2026
She was willing to give up the lifestyle she knew and enjoyed in favor of moving to an independent living community closer to her daughter in New England.
From MarketWatch ● Jul. 12, 2026
I never knew she was referring to a real place.”
From "Legendary Frybread Drive-In" by Cynthia Leitich Smith
Sam Neill, the New Zealand actor known for his roles in ‘Jurassic Park,’ ‘The Piano’ and ‘Hunt for the Wilderpeople’ has died.
From Los Angeles Times ● Jul. 13, 2026
The court in Port Sudan, a city under the army's rule, convicted Dagalo - known as Hemedti - in absentia, along with 15 other senior RSF members, who were given the same sentence.
From BBC ● Jul. 13, 2026
Tech borrowing only kicked off in earnest last fall, when the megacap Big Tech companies known as hyperscalers started to voraciously issue debt.
From MarketWatch ● Jul. 13, 2026
Beginning in December 1913, at the age of 55, he co-led an expedition to chart a tributary of the Amazon that is today known as the Rio Roosevelt.
From The Wall Street Journal ● Jul. 13, 2026
He never knew me the way Nate seems to have always known me.
From "Red Flags and Butterflies" by Sheryl Azzam
“I feel like I’m continuing to get better at knowing where to go with two strikes, knowing where to go versus a certain hitter with two strikes and just kind of reading the game.”
From Los Angeles Times ● Jul. 13, 2026
But there’s an optimism in knowing for sure that the jig is up.
From Salon ● Jul. 13, 2026
Everyone is one call, text or click away from knowing everything about you.
From The Wall Street Journal ● Jul. 12, 2026
“Financial independence is controlling your own future,” said Greg Welborn, an adviser in Pasadena, Calif. “It’s knowing if you lost your income, how you’d recover.”
From MarketWatch ● Jul. 12, 2026
Unfortunately, the Phrenologists have no way of knowing which part of the brain controls what.
From "Phineas Gage" by John Fleischman
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.
