un·​known | \ ˌən-ˈnōn How to pronounce unknown (audio) \

Definition of unknown

 (Entry 1 of 2)

: not known or not well-known also : having an unknown value an unknown quantity



Definition of unknown (Entry 2 of 2)

1 : one that is not known or not well-known especially : a person who is little known (as to the public)
2 : something that requires discovery, identification, or clarification: such as
a : a symbol (such as x, y, or z) in a mathematical equation representing an unknown quantity
b : a specimen (as of bacteria or mixed chemicals) required to be identified as an exercise in appropriate laboratory techniques

Synonyms for unknown

Synonyms: Adjective

Visit the Thesaurus for More 

Examples of unknown in a Sentence

Adjective a disease of unknown cause Much remains unknown about his early life. Her music was previously unknown outside of Asia. An unknown number of cases go unreported. The victim's attacker was unknown to her. For some unknown reason, my computer crashed. a book of unknown poems Noun explorers venturing off into the unknown A fear of the unknown kept her from changing jobs. The director cast an unknown in the lead role. We're facing too many unknowns.
See More
Recent Examples on the Web: Adjective Investigators were able to make contact with the woman, but said her condition was unknown, according to officials. Jamie Goldberg, oregonlive, 16 Jan. 2022 The extent of her injuries was unknown, Hisaw said. David Hernandez, San Diego Union-Tribune, 16 Jan. 2022 The full roster is still unknown, but reports are slowly rolling in. ELLE, 16 Jan. 2022 All are embracing the unknown — and hoping for the best. David Browne, Rolling Stone, 12 Jan. 2022 Deconstruction is not something that people do exactly, but rather something that happens, often when people commit to the unknown and the impossible. Audrey Clare Farley, The New Republic, 3 Jan. 2022 The primary cause behind 35% of such incidents is unknown. Elliot Hughes, Milwaukee Journal Sentinel, 4 Jan. 2022 Federal prosecutors have said those charges are being handled by state authorities, and the status of that separate case is unknown. Bill Donahue, Billboard, 4 Jan. 2022 Ward suffered a groin injury in the second half, and his status for the Bengals game is unknown. cleveland, 4 Jan. 2022 Recent Examples on the Web: Noun Ali Khara / Reuters Already vulnerable after months of severe drought and decades of war that forced many to flee homes for relatively stable regions like Bamiyan, Afghans are entering the unknown. NBC News, 30 Dec. 2021 Kind declined to predict how House Democrats will do next November, citing the unknown on COVID-19 and the economy. Aaron Navarro, CBS News, 24 Dec. 2021 Effective leaders foster a sense of belonging, of safety within the team, building the trust that transforms the fear and ambiguity of facing the unknown into the excitement of possibility, challenge and performance. Mark Attard, Forbes, 21 Dec. 2021 The emergence of the omicron variant represents a major unknown. Washington Post, 21 Dec. 2021 But the 2022 race will face an unknown not seen before in modern Oregon politics. oregonlive, 18 Dec. 2021 Randy and Doc are having a true adventure where the unknown becomes the experience. Joe Michaud, San Diego Union-Tribune, 17 Dec. 2021 Then essentially an unknown, Del Toro didn’t get very far in acquiring the rights. Mark Olsen, Los Angeles Times, 17 Dec. 2021 Another Omicron unknown is the share of Covid cases in the U.S. that involve the new variant. Nicholas St. Fleur, STAT, 15 Dec. 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'unknown.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of unknown


14th century, in the meaning defined above


1597, in the meaning defined at sense 1

Learn More About unknown

Time Traveler for unknown

Time Traveler

The first known use of unknown was in the 14th century

See more words from the same century

Dictionary Entries Near unknown



unknown quantity

See More Nearby Entries 

Statistics for unknown

Last Updated

18 Jan 2022

Cite this Entry

“Unknown.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unknown. Accessed 27 Jan. 2022.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

More Definitions for unknown



English Language Learners Definition of unknown

 (Entry 1 of 2)

: not known
: not well-known : not famous



English Language Learners Definition of unknown (Entry 2 of 2)

: a place, situation, or thing that you do not know about or understand
: a person who is not famous or well-known
: something that is not known or not yet discovered


un·​known | \ ˌən-ˈnōn How to pronounce unknown (audio) \

Kids Definition of unknown

 (Entry 1 of 2)

: not known … it was cut all over with strange lines and figures that might be the letters of an unknown language.— C. S. Lewis, The Lion, The Witch and The Wardrobe



Kids Definition of unknown (Entry 2 of 2)

: one (as a quantity) that is unknown

More from Merriam-Webster on unknown

Nglish: Translation of unknown for Spanish Speakers

Britannica English: Translation of unknown for Arabic Speakers


Test Your Vocabulary

Name that Thing: Flower Edition

Spell It

Can you spell these 10 commonly misspelled words?

Universal Daily Crossword

A daily challenge for crossword fanatics.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!