From Old English 'cnawan' and PIE *gneh3- (to know) — same root as 'cognition,' 'gnosis,' and 'ignorance.'
To be aware of through observation, inquiry, or information; to have a clear perception or understanding of a fact or truth.
From Old English cnāwan (to know, perceive, recognize), from Proto-Germanic *knēaną, from PIE *ǵneh₃- (to know, to recognize). This is one of the most prolific roots in all of Indo-European, producing Latin gnōscere/nōscere (to know, whence cognition, recognize, notion), Greek gignṓskein (to know, whence diagnosis, prognosis, gnostic), Sanskrit jñā- (to know, whence jñāna 'knowledge'), Old Irish gnáth (known, customary), and Old Church Slavonic znati (to know). The initial kn- cluster was fully pronounced in Old and Middle English; the /k/ fell silent only in the 17th century, leaving know, knee