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
- knowable adjective
- knower noun
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”; 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.
Those men know power, and know how to use it.
From Los Angeles Times • Apr. 14, 2026
"I don't know, I have heard many things, I have no word to talk about that because with the World Cup coming it is very, very hard for him and I send him my prayers."
From BBC • Apr. 14, 2026
To start the week Oracle broke above a bearish descending triangle, and we know from false moves come fast ones in the opposite direction.
From Barron's • Apr. 14, 2026
“I know you don’t want me to be your coach,” he remembers telling the Lakers squad that he did coach between 1976 and 1979.
From The Wall Street Journal • Apr. 14, 2026
They know how I feel about you, how I feel about you, how I feel about you.
From "Legendary Frybread Drive-In" by Cynthia Leitich Smith
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.
