know / nō/ • v. (past knew / n(y)oō/ ; past part. known / nōn/ ) 1. be aware of through observation, inquiry, or information: most people know that CFCs can damage the ozone layer. ∎  [tr.] have knowledge or information concerning: I would write to him if I knew his address | [intr.] I know of one local who shot himself. ∎  be absolutely certain or sure about something: I just knew it was something I wanted to do | [tr.] I knew it! 2. [tr.] have developed a relationship with (someone) through meeting and spending time with them; be familiar or friendly with: he knew and respected Laura. ∎  have a good command of (a subject or language). ∎  recognize (someone or something): Isabel couldn't hear the words clearly, but she knew the voice. ∎  be familiar or acquainted with (something): a little restaurant she knew near Times Square. ∎  have personal experience of (an emotion or situation): a man who had known better times. ∎  (usu. be known as) regard or perceive as having a specified characteristic: he is also known as an amateur painter. ∎  (usu. be known as) give (someone or something) a particular name or title: the doctor was universally known as “Hubert.” PHRASES: be in the know be aware of something known only to a few people: he had a tip from a friend in the know: the horse was a sure bet.know one's own mind be decisive and certain.know one's way around be familiar with (an area, procedure, or subject).DERIVATIVES: know·a·ble adj.know·er n.ORIGIN: Old English cnāwan (earlier gecnāwan) ‘recognize, identify,’ of Germanic origin; from an Indo-European root shared by Latin (g)noscere, Greek gignōskein.