[1] : The Collaborative International Dictionary of English v.0.48

unbeknown \un`beknown"\, a.
   not known; unknown. colloq.
   1913 webster

[2] : WordNet (r) 2.0

unbeknown
     adj : usually used with `to' occurring or existing without the
           knowledge of; "a crisis unbeknown to me"; "she had been
           ill for months, unbeknownst to the family" syn: unbeknownp,
            unbeknownstp
     adv : without someone's knowledge; "unbeknownst to me, she made
           all the arrangements" syn: unbeknownst
see also:
unbeknownp unbeknownstp unbeknownst 

[3] : Moby Thesaurus II by Grady Ward, 1.0

34 moby thesaurus words for "unbeknown":
   able, enigmatic, incalculable, incognizable, mysterious, puzzling,
   sealed, strange, unapparent, unapprehended, unascertained,
   uncharted, unclassified, undisclosed, undiscoverable, undiscovered,
   undivulged, unexplained, unexplored, unexposed, unfamiliar,
   unfathomed, unheard, unheard-of, unidentified, uninvestigated,
   unknowable, unknown, unperceived, unplumbed, unrevealed,
   unsuspected, untouched, virgin

Unbeknown >> U Words
Unbeknown, definition of term: Unbeknown
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