not know from Adam

To not know who one is just by looking at them; to have never met someone before. Even though Jake had worked at the company for nearly 10 years, the boss still didn't know him from Adam. I don't blame them for not giving me permission right away. They don't know me from Adam.

Fig. not to know someone by sight at all. I wouldn't recognize John if I saw him up close. I don't know him from Adam. What does she look like? I don't know her from Adam.

Not acquainted with someone. The Adam referred to in this mid-nineteenth century term is the first human being according to the Book of Genesis. One writer suggests that the inability to recognize Adam is the height of foolishness, since he had no name and wore only a fig leaf, but this point does not seem particularly relevant. The French have a similar saying that includes Eve as well (“Je ne connais ni d’Eve ni d’Adam”).

See know from Adam.