See more synonyms for unbeknown on Thesaurus.com
Also un·be·knownst [uhn-bi-nohnst] /ˌʌn bɪˈnoʊnst/.

Origin of unbeknown

1630–40; un-1 + beknown (late Middle English beknowe, past participle of beknowen); see be-, known
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for unbeknownst

Contemporary Examples of unbeknownst

Historical Examples of unbeknownst

  • That's 'bout the only way he'll ever do one, Frank, unbeknownst like.

    Old Man Curry

    Charles E. (Charles Emmett) Van Loan

  • Unbeknownst to her, Mildred would be protected against these dangers.

  • But unbeknownst to it, this very violence thrived on these pecuniary fertilizers.

    After the Rain

    Sam Vaknin

  • Some of them carriers, I expect, puttin' their horses in unbeknownst to you.

    An Outback Marriage

    Andrew Barton Paterson

  • Unbeknownst to yourself, dear, you bore him what he wanted, and what I wanted.

    The Soul of Susan Yellam

    Horace Annesley Vachell

British Dictionary definitions for unbeknownst


  1. (sentence modifier foll by to) without the knowledge (of a person)unbeknown to him she had left the country Also (esp Brit): unbeknownst
  1. (postpositive usually foll by to) rare not known (to)

Word Origin for unbeknown

C17: from the archaic beknown known; see be-, know
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for unbeknownst

1833, vulgar formation from unbeknown (1630s). No clear reason for the -st, but since 19c. this has become the dominant form.



1630s, from un- (1) "not" + beknown (see beknow).

Online Etymology Dictionary, © 2010 Douglas Harper