un‧be‧known /ˌʌnbɪˈnəʊn $ -ˈnoʊn/ (
also un‧be‧knownst /-ˈnəʊnst $ -ˈnoʊnst/
written)
adverb [sentence adverb] unbeknown to somebody without that person knowing about it:
Unbeknown to him, his wife had been trying to phone him all morning. [TahlilGaran] Dictionary of Contemporary English ▲