unknown

The word “unknown” means not known, identified, or familiar. In plain terms, not identified or not yet found out — as an adjective describing a fact, or a noun for the thing itself.

“Unknown” is pronounced uh-nohn (/ʌnˈnoʊn/ in IPA).

Here is “unknown” used in a sentence: “The cause of the fire is still unknown.”

The opposite of “unknown” — its antonyms — are ascertained, familiar, famous, known and recognizable.

Depending on how it is used, “unknown” can be an adjective and a noun.

The word “unknown” comes from Old English. From Old English ungecnawen, from "un-" + "known.".

“Unknown” is a fairly common word in modern English, usually learned at around the A2 level.

“Unknown” has 3 distinct senses listed in this dictionary. The most common is: not known, identified, or familiar.

Unknown means not known, identified, or familiar in a general sense, applying to facts, places, or people. Anonymous specifically means a name is deliberately withheld or unavailable, as with an anonymous donor. Something can be unknown simply because no one has discovered it, while anonymous implies an identity exists but is hidden.

The main opposites are 'known,' 'familiar,' and 'identified.' Depending on context, you might also use 'famous' or 'renowned' when contrasting an unknown person with a celebrity. The right opposite depends on whether you mean something not yet discovered, not recognised, or simply not well known to the public.

As a noun, 'the unknown' refers to everything that has not been discovered, understood, or experienced, often carrying a sense of mystery or uncertainty. People speak of 'fear of the unknown' when they feel anxious about what lies ahead. In maths, an unknown is also a value you are trying to find.