unknown

unknown — adjective

1. not seen, met, or learned about before; having no information about something or

1.adjectiveA2
Definition

not seen, met, or learned about before; having no information about something or someone.

Example

The cause of the fire remained unknown to the investigators for several weeks.

remain unknown to [someone]

Theo arrived in a city where the language and customs were completely unknown to him.

completely unknown to [someone]

Common collocations
  • unknown to
  • remain unknown
  • keep something unknown
  • unknown reason
  • unknown sender
Synonyms
  • unfamiliar

    stronger focus on personal lack of experience; 'unfamiliar' usually describes something you personally have not encountered before.

  • mysterious

    adds an implication that the thing is strange, secret, or hard to understand.

  • unidentified

    used when a specific name, origin, or type has not been determined; common in news reports.

Antonyms
  • known

    direct opposite; means having information about or familiarity with something.

  • familiar

    suggests personal knowledge and recognition from past experience.

Grammar Patterns

unknown + to + noun phrase

remain + unknown

unknown + noun

Common Mistakes

The reason is unknown with me.
The reason is unknown to me.
'unknown' takes the preposition 'to', not 'with'.
I am unknown of that fact.
That fact is unknown to me.
'unknown' describes the thing not known, not the person who lacks knowledge.

2. not having achieved fame or wide public recognition; used for people, or the wor

2.adjectiveB1
Definition

not having achieved fame or wide public recognition; used for people, or the work they produce, that few people know about.

Example

At that time, Élise was an unknown actress working small roles in local plays.

unknown + noun (person not famous)

The band started as a group of unknown musicians playing in a small club.

Common collocations
  • relatively unknown
  • completely unknown
  • still unknown
  • unknown actor
  • unknown artist
Synonyms
  • obscure

    suggests even less public awareness and sometimes a lack of available information about the person or thing.

  • little-known

    milder in tone, simply indicating that few people have heard of someone or something.

  • unsung

    positive connotation; implies the person deserves more recognition than they receive.

Antonyms
  • famous

    direct opposite; means known to many people.

  • well-known

    familiar to a large number of people.

  • celebrated

    widely praised and recognised.

Grammar Patterns

unknown + noun

relatively + unknown

still + unknown

Usage Note

Frequently used with adverbs such as 'relatively', 'completely', and 'still' to indicate the degree of obscurity.

Common Mistakes

She was unknown actress in 2019.
She was an unknown actress in 2019.
'unknown' needs the article 'an' before a singular countable noun.
Idioms

an unknown quantity

idiom

A person or thing whose character or skills have not been discovered yet.

The new player is an unknown quantity, but the coach is hopeful.

Is the candidate an unknown quantity for the voters?

unknown to somebody

idiom

Happening without the person mentioned knowing about it.

Unknown to her parents, Maya had already booked the flight.

Did Diego leave the party unknown to his friends?

unknown — noun

Word family

Synonym discussion

Sense: adjective/1

All five words describe a lack of knowledge, but for different reasons and in different tones. 'Unknown' is the broadest and most neutral term — it simply states that no information exists about something (The cause of the accident remains unknown). 'Unfamiliar' focuses on personal experience: you may not know something even though others do (I am unfamiliar with this software). 'Mysterious' adds a layer of intrigue or strangeness — it suggests that the thing is hard to understand or deliberately hidden (A mysterious figure stood at the gate). 'Unidentified' is used when a specific name or classification has not been assigned, common in official reports (The police found an unidentified body in the river). 'Obscure' leans more toward the 'not famous' end of the scale, meaning very few people have access to the information or know about the subject (He collects obscure jazz records from the 1950s). Use 'unknown' for simple lack of information, 'unfamiliar' for gaps in personal knowledge, 'mysterious' when the unknown is puzzling, 'unidentified' when a label is missing, and 'obscure' when something is hard to discover or little-known.

unknown ↗unfamiliar ↗mysterious ↗unidentified ↗obscure ↗

Common collocations

Nouns

  • unknown cause
  • unknown sender
  • unknown origin
  • unknown quantity
  • unknown territory

Adverbs

  • completely unknown
  • relatively unknown
  • largely unknown
  • still unknown
  • previously unknown
  • entirely unknown

Phrases

Prepositions

  • unknown to

Etymology

Proto-Indo-EuropeanGermanicOld EnglishMiddle EnglishEnglish

The word 'unknown' was formed in Old English (before the 12th century) by adding the negative prefix 'un-' to the past participle 'known'. The prefix 'un-' comes from Germanic origins and has been used in English since the earliest records to reverse the meaning of adjectives and participles. The root 'know' traces back to Old English 'cnāwan', from the Proto-Germanic *knēanan, and ultimately to the Proto-Indo-European root *gno- meaning 'to know'. The same PIE root appears in Latin 'gnoscere' (to know) and Greek 'gignōskein' (to know), giving English words such as 'recognize', 'diagnosis', and 'ignore'.