unbeknownst /ˌʌnbɪˈnoʊnst/ adjective or unbeknown /ˌʌnbɪˈnoʊn/ or unbeknown /ˌʌnbɪˈnoʊn/ Learner's definition of UNBEKNOWNST
unbeknownst/unbeknown to
: without being known about by (someone)不为(某人)所知的;瞒着(某人)的 ◊ In U.S. English unbeknownst is more common than unbeknown. In British English, unbeknown is more common.在美国英语中,unbeknownst比unbeknown更常用。在英国英语中,unbeknown更常用。