unknown

1 of 2

adjective

un·​known ˌən-ˈnōn 

: not known or not well-known

also : having an unknown value

an unknown quantity

unknown

2 of 2

noun

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

Adjective

• unbeknownst
• unbeknown

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.

Recent Examples on the Web

Adjective

The causes of dementia are still largely unknown, but scientists have identified factors that can increase the risk of developing it, such as genes and lifestyle choices. —Sherri Gordon, Health, 14 May 2024

The status of the unit today is unknown because Israel has dealt a significant blow to Hamas’s military and governing abilities. —Ronen Bergman, New York Times, 13 May 2024

Word History

First Known Use

Adjective

14th century, in the meaning defined above

Noun

1597, in the meaning defined at sense 1

Phrases Containing unknown

• big unknown
• fear of the unknown
• of unknown origin
• the unknown
• unknown quantity
• unknown to

Kids Definition

unknown

1 of 2 adjective

un·​known ˌən-ˈnōn 

: not known

also : having an unknown value

an unknown quantity

unknown

2 of 2 noun

1

: something that is unknown

2

: a symbol (as x, y, or z) representing a quantity whose value is unknown

an equation with two unknowns