know

Etymology

From Middle English knowen, from Old English cnāwan (“to know, perceive, recognise”), from Proto-West Germanic *knāan, from Proto-Germanic *knēaną (“to know”), from Proto-Indo-European *ǵneh₃- (“to know”). cognates * from Proto-Germanic: Scots knaw (“to know, recognise”), Icelandic kná (“to know, know how to, be able”), Old High German knājan (“to know, recognise”), Old Norse kná (“to know how”). Remotely related also Dutch and German kennen, West Frisian kenne (see English ken). * from Indo-European: Latin cognoscō (Spanish conocer, French connaître, Italian conoscere, Portuguese conhecer), Ancient Greek γνωρίζω (gnōrízō, “I know”) and γνῶσις (gnôsis, “knowledge”), Albanian njoh (“I know, recognise”), Russian знать (znatʹ, “to know”), Lithuanian žinoti (“to know”), and Persian شناختن (šenâxtan, “to know”).

verb

1. (transitive) To perceive the truth or factuality of; to be certain of or that.
   Question things. I have the most fun when I'm writing questioning things that people do not question- the assumptions that everybody knows are true. 4/17/1985, Frank Herbert, 15:46 from the start, in Frank Herbert speaking at UCLA 4/17/1985, UCLACommStudies, archived from the original on 2017-02-10
   I know that I’m right and you’re wrong.
   He knew something terrible was going to happen.
2. (transitive) To be aware of; to be cognizant of.
   Did you know Michelle and Jack were getting divorced? ― Yes, I knew.
   She knows where I live.
   I knew he was upset, but I didn't understand why.
3. (transitive) To be acquainted or familiar with; to have encountered.
   I know your mother, but I’ve never met your father.
   Marsha is my roommate. — I know Marsha. She is nice. Audio (US) (file) 2016, VOA Learning English (public domain)
4. (transitive) To experience.
   Their relationship knew ups and downs.
   The Truman family knew good times and bad,[…]. 1991, Irvin Haas, Historic Homes of the American Presidents, page 155
5. (transitive) To be able to distinguish, to discern, particularly by contrast or comparison; to recognize the nature of.
   to know a person's face or figure
   to know right from wrong
   I wouldn't know one from the other.
   Flares do not know friend from foe and so illuminate both. Changes in wind direction can result in flare exposure of the attacker while defenders hide in the shadows. 1980, Armored and mechanized brigade operations, p.3−29
6. (transitive) To recognize as the same (as someone or something previously encountered) after an absence or change.
   At nearer view he thought he knew the dead, / And call'd the wretched man to mind. c. 1645-1688, Thomas Flatman, Translation of Part of Petronius Arbiter's Satyricon
7. To understand or have a grasp of through experience or study.
   Let me do it. I know how it works.
   She knows how to swim.
   His mother tongue is Italian, but he also knows French and English.
   She knows chemistry better than anybody else.
   Know your enemy and know yourself.
   The yawning gap in neuroscientists’ understanding of their topic is in the intermediate scale of the brain’s anatomy. Science has a passable knowledge of how individual nerve cells, known as neurons, work. It also knows which visible lobes and ganglia of the brain do what. But how the neurons are organised in these lobes and ganglia remains obscure. 2013-08-03, “The machine of a new soul”, in The Economist, volume 408, number 8847
8. (transitive, archaic, biblical) To have sexual relations with. This meaning normally specified in modern English as e.g. to ’know someone in the biblical sense’ or to ‘know biblically.’
   Now Gerald had never thought of her having a mother. Then there must have been a father, too, some time. And Miss Wilmarth existed because two people once had loved and known. It was not a thought to dwell upon. 1939, Dorothy Parker, “Horsie,”, in Here lies: The collected stories of Dorothy Parker
   Wait a second. Are you… attempting to know me? May 11, 2003, Garland Testa, 19:37 from the start, in Gary McCarver, director, Night and Deity (King of the Hill), season 7, episode 21, spoken by Dale Gribble (Johnny Hardwick), 20th Century Fox
9. (intransitive) To have knowledge; to have information, be informed.
   It is vital that he not know.
   She knew of our plan.
   He knows about 19th century politics.
   Manganism has been known about since the 19th century, when miners exposed to ores containing manganese, a silvery metal, began to totter, slur their speech and behave like someone inebriated. 2014-04-21, “Subtle effects”, in The Economist, volume 411, number 8884
   Marsha knows. Audio (US) (file) 2016, VOA Learning English (public domain)
10. (intransitive) To be or become aware or cognizant.
    Did you know Michelle and Jack were getting divorced? ― Yes, I knew.
11. (intransitive, obsolete) To be acquainted (with another person).
12. (transitive) To be able to play or perform (a song or other piece of music).
    Do you know "Blueberry Hill"?
13. (transitive) To have indexed and have information about within one's database.
    Mmm... Seems you searched for a name that we don't know, we'll send our trained monkeys to check what's in stock. June 7, 2023, “Search Names and Meanings”, in Name Doctor, archived from the original on 2023-06-07

noun

1. (rare) Knowledge; the state of knowing.
2. Knowledge; the state of knowing; now confined to the fixed phrase ‘in the know’