know
1 Americanverb (used with object)
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knows,
present (3rd person singular)
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knew,
past
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known,
past participle
-
knowing
present participle
-
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)
-
knows,
present (3rd person singular)
-
knew,
past
-
known,
past participle
-
knowing
present participle
-
to have knowledge or clear and certain perception, as of fact or truth.
-
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:
Here is what we know about Panettiere’s death.
From Los Angeles Times ● Aug. 17, 2026
A chance to flex your big vocabulary: Do you know which activity a pugilist engages in?
From Slate ● Aug. 17, 2026
"Kyle has to know that if you lose the ball it's a goal," Guardiola tells his dressing room afterwards, which draws an angry reaction from the defender, who says: "Every meeting, it's my name".
From BBC ● Aug. 17, 2026
Although you might find even that high a probability to be alarming, you should know that the average of those probabilities over the last five years has been 26%.
From MarketWatch ● Aug. 17, 2026
There’s only been one incident that I know of where someone tried to change a red Flash—my great-aunt Betsy.
From "Split the Sky" by Marie Arnold
She knows the central irony of her situation: Just because she and her mother are refusing to sell their land doesn’t mean the data center won’t be built.
From The Wall Street Journal ● Aug. 16, 2026
"But no one knows for sure what will happen or not. You just rely on your intuition and survival instinct," the 34-year-old said.
From Barron's ● Aug. 16, 2026
Purists might refer to it as ulnar collateral ligament reconstruction, but the rest of the world knows it as the career-saving surgery named for a sore-armed left-handed Dodgers pitcher.
From Los Angeles Times ● Aug. 16, 2026
Who knows if the English game will be marching on together as hoped by those that have staked so much on this direction?
From BBC ● Aug. 16, 2026
She knows I’ve been away for way too long.
From "Split the Sky" by Marie Arnold
“If I messed up, what would people think of me? What would Mom say? I knew it wouldn’t be good.”
From The Wall Street Journal ● Aug. 17, 2026
It made me laugh so hard, I knew from that point on that he was a kindred spirit.
From Los Angeles Times ● Aug. 17, 2026
More recently, she knew that outbreaks were "rife" in England and had seen stories shared on social media and in the news.
From BBC ● Aug. 17, 2026
I knew the renter, and everything was going well.
From MarketWatch ● Aug. 17, 2026
Aristotle, the greatest scientist of his time, "knew" that the primary function of the brain was to cool the blood.
From "Phineas Gage" by John Fleischman
Hayden Panettiere, the accomplished former child actor known for roles in ‘Ice Princess’ and ‘Heroes,’ died Sunday at age 36.
From Los Angeles Times ● Aug. 17, 2026
The Japanese macaque - also known as a snow monkey - is about the size of a medium-sized dog once it reaches adulthood.
From BBC ● Aug. 17, 2026
That narrative betrays a rookie mistake that’s known among statisticians as the “gambler’s fallacy.”
From MarketWatch ● Aug. 17, 2026
Navy’s only aircraft carrier in the entire region known as Asia Pacific.
From Slate ● Aug. 17, 2026
I’ve known for three years now that I’m gluten intolerant.
From "Red Flags and Butterflies" by Sheryl Azzam
In the 200m in particular, she takes great confidence in knowing few can match her in the closing stages.
From BBC ● Aug. 17, 2026
Especially knowing full well that all that interrogation could ever reveal was a bottomless shame that nobody—and certainly not themselves—could atone for?
From Slate ● Aug. 17, 2026
The norm at U.S. companies is for management to gild the lily, knowing the analysts at big Wall Street brokers will relay the spin as their own.
From The Wall Street Journal ● Aug. 14, 2026
Nobody wears a Speedmaster not knowing where it’s been.
From Los Angeles Times ● Aug. 14, 2026
I steal a quick glance at him, knowing what he’s going to say.
From "Red Flags and Butterflies" by Sheryl Azzam
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.
