adj.
Pronunciation: ˌ ə n-bi- ' n ō n(t)st
Variant: also un · be · known \ - ' n ō n \
Function: adjective
Etymology: 1 un- + obsolete English beknown known; unbeknownst, irregular from unbeknown
Date: 1636
1 : happening or existing without the knowledge of someone specified ― usually used with to < unbeknownst to us rumors were flying>
2 : UNKNOWN