unknown
adj. · n.-
1 not identified (adj.) B2 Upper Intermediatenot known, identified, or familiar to people.
not known, identified, or familiar; often used postpositionally in specific phrases like 'reasons unknown'.
ExampleThe letter was sent by an unknown person with no return address.
ExampleThe painting was attributed to an unknown artist from the seventeenth century, though recent stylistic analysis suggests a student of Rembrandt.
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2 the mysterious or unexplored (n.) B2 Upper Intermediatea place, situation, or fact that nobody knows anything about yet.
an unexplored or unidentified place, situation, or realm of knowledge; often used with the definite article 'the'.
ExampleSpace travel is a journey into the unknown for most of us.
ExampleThe explorers faced the great unknown with a mixture of trepidation and scientific curiosity, unsure of what the deep-sea trenches might reveal.
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3 a person without fame (n.) C1 Advanced Formala person who is not famous or whose identity is not known.
an individual who lacks fame, social standing, or a public identity.
ExampleHe was a complete unknown before he won the national talent show.
ExampleThe candidate was a political unknown until a series of viral debates propelled her to the forefront of the national conversation.
- nobody
- nonentity
- celebrity
- public figure
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4 math variable (n.) B2 Upper Intermediate Technical Matha symbol, like x or y, that represents a number you need to find.
a quantity or variable in a mathematical equation whose value is initially unspecified and must be determined.
ExampleIn the equation 2x + 5 = 11, x is the unknown.
ExampleThe physicist introduced a second unknown into the formula to account for the unexpected variance in gravitational pull during the experiment.
From Middle English unknowen, uniknowen, uniknowe, from Old English unġecnāwen (“unknown”), equivalent to un- + known.