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 ); be-, known

Example Sentences

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

From The Wall Street Journal

A week earlier Sturdivant had also begun communicating on a social-media platform with someone who, unbeknown to him, was an undercover officer.

From The Wall Street Journal

The cap had been, unbeknown to the family, in an office in Dublin until July, when it was reunited with the Goodall family.

From BBC

The document shows that unbeknown to sub-postmasters, the two parties had a financial framework in place to manage discrepancies and for Fujitsu to fix problems or pay for them.

From BBC

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

From Los Angeles Times