unbeknown
🇺🇸
/ˌʌnbɪˈnəʊn/
🇬🇧
/ˌʌnbɪˈnəʊn/
without someone's knowledge or awareness
Unbeknown to him, his friends had planned a trip.
他不知道,他的朋友們計畫了一次旅行。