unbeknown

American  

[uhn-bi-nohn] / ˌʌn bɪˈnoʊn /

Also unbeknownst

adjective

1. unknown; unperceived; without one's knowledge (usually followed byto ).

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unbeknown British  

/ ˌʌnbɪˈnəʊn /

adverb

1. Also (esp Brit): unbeknownst.  without the knowledge (of a person)

   unbeknown to him she had left the country

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adjective

1. rare not known (to)

Etymology

Origin of unbeknown

1630–40; un- ¹ + beknown ( late Middle English beknowe, past participle of beknowen ); see be-, known

Example Sentences

These were simple concepts to understand, but unbeknown to almost everybody for generations, they might have been flawed.

From The Wall Street Journal • Apr. 16, 2026

But unbeknown to them, a little-known developer was readying a proposal that could transform the Marina’s skyline.

From The Wall Street Journal • Jan. 18, 2026

So how did the Earwigs gain this unlikely cult following unbeknown to its founding member?

From Los Angeles Times • Sep. 6, 2025

It was not something they had discussed but, unbeknown to them, Macauley had signed the organ donor register, twice.

From BBC • Sep. 22, 2024

We were waiting for Mr. Mwakangale of the Tanganyika African National Union, a member of Parliament, and unbeknown to us he had already called looking for us.

From "Long Walk to Freedom" by Nelson Mandela