unknown

Pluralunknowns

1. 1
   adjective

   Not known or identified, or not widely recognized or familiar.

   The painting's artist remains unknown to this day.

   She rose from an unknown singer to an international star in two years.

   Similarunfamiliar, unidentified, obscure, anonymous, unnamed

   Oppositeknown, famous

   Note

   An old formation that English has kept: Old English unġecnāwen, later Middle English uniknowe, built from un- plus known. Usually it stands before its noun (an unknown artist), but it can also follow it, as in "by arts unknown" in the American novelist Winston Churchill's The Celebrity (1897). After a verb it often takes to, naming who is in the dark: a system that "remains unknown to many people." It compares with more and most.

2. 2
   nouncountable or uncountable

   A thing, place, or situation about which nothing is known; a fact that has not yet been discovered.

   Every mission into deep space confronts explorers with the unknown.

   The report listed several unknowns that the engineers still had to investigate.

   Similarmystery, uncertainty

   Oppositeknown

   Note

   The noun works in two ways. With the and no plural, it names whatever lies beyond knowledge, as in "into the unknown" or "a shield against the unknown." As a countable noun it names a specific gap in planning, as in "one of the biggest unknowns." Donald Rumsfeld's "known unknowns" plays on the countable use: gaps we know we have.

3. 3
   nouncountable

   A variable, usually written x, y, or z, whose value must be determined.

   Each equation in the system contains two unknowns to solve for.

   Isolate the unknown on one side of the equation before substituting values.

   Similarvariable

   Note

   Algebra treats this as a countable noun: an equation or system is described by how many unknowns it holds, and you solve for them one by one. The letters x, y and z are a convention, not a rule. Compare the general sense of the unknown, which often appears as an abstract noun with the. Here the noun counts freely, and unknowns is its ordinary plural.

4. 4
   nouncountable

   A person who has no public identity or importance; a nonentity.

   The election was won by a political unknown from a small town.

   Critics dismissed the director as an unknown with no track record.

   Similarnobody, nonentity, newcomer, outsider

   Oppositecelebrity, somebody, star

   Note

   Here the noun turns personal and countable: someone without name or standing, often intensified with complete, as Bob Dylan does in "Like a Rolling Stone" (1965). It can also describe the anonymous dead. Syed Waliullah's Tree Without Roots speaks of "the neglected burial-place of an unknown." Its natural opposites are famous and well-known.

5. 5
   verb

   Past participle of unknow.

   Some truths, once grasped, can never be unknown.

   He wished the secret could be unknown, but knowledge does not retreat so easily.

   Note

   The spelling is shared with the everyday adjective, but here it is the participle of unknow, to lose knowledge of something. The difference shows most clearly after be. "Some truths can never be unknown" means they cannot be forgotten once learned, not that they are unfamiliar. Context, not form, tells the two apart.

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