(adj) not knowledgeable about something specified, Syn. unacquainted, Example:American tourists wholly innocent of French; a person unacquainted with our customs
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
[素昧平生, sù mèi píng shēngㄙㄨˋ ㄇㄟˋ ㄆㄧㄥˊ ㄕㄥ] to have never met sb before (成语 saw); entirely unacquainted; a complete stranger; not to know sb from Adam#62922