Not know or be completely unable to recognize the person in question.
More example sentences
- There's nothing more transparent than a politician smiling and greeting you like a long lost friend when you know well he doesn't know you from Adam.
- If you bank in the high street the person behind the counter doesn't know you from Adam.
- And despite the fact that he doesn't know me from Adam, he is prepared to trust me with all that money.
Definition of not know someone from Adam in:
- The British & World English dictionary