not acquainted
You don't even know her.
You don't know them, do you?
We don't know each other.
Мы с Томом не знакомы.
Tom and I don't know each other.
Вы с ним действительно не знакомы?
You really don't know him?
You don't know him.
Но между прочим, они притворились, будто не знакомы.
But incidentally, they pretended not to know each other.
— Развод по-итальянски (1961)
We don't even know them.