unbeknown Meaning, Definition & Usage

1. adjective satellite (usually used with `to') occurring or existing without the knowledge of
   unbeknownst.
   
   • a crisis unbeknown to me
   • she had been ill for months, unbeknownst to the family
2. adverb without someone's knowledge
   unbeknownst.
   
   • unbeknownst to me, she made all the arrangements

WordNet