known

Known is the past participle of the verb know and an adjective used to describe something that has been recognized, identified, or is familiar. In everyday language it appears in phrases such as the known facts, a well-known author, or a known issue.

The word known derives from Old English cnawan, and its past participle was formed with a prefix in the historical development of English. It is related to German kennen and Dutch kennen, all sharing a Proto-Germanic origin for "to know."

As an adjective, known denotes knowledge that is established or commonly accepted, and it can refer to information that is publicly acknowledged or already discovered. As the past participle of know, it is used in perfect tenses and in phrases such as "the known universe" or "the known errors."

In epistemology and related fields, the concept of knowledge is central, and "known" is used to describe propositions that are true and justified. In epistemic logic, the operator Kp signifies that p is known by an agent.

Known also functions as a surname or as part of names and branding. In common expressions such as "known unknowns," the term contrasts what is certain with what remains to be discovered.