He looked 'familiar' [=he looked like someone I had seen before] but I couldn't remember his name.
Locals refer to the Maple Leaf restaurant 'familiarly' [='informally'] as ‘The Leaf.’
We are 'familiar with' the situation. [=we know about the situation]
(..) for instance, supposing I told you that your fly was undone? By remarkable coincidence, so is yours. Oh, no, not again. Ah, I see you are familiar with the "open fly" ploy. Well, so am I. Oh, you are so naughty. "Falling on the bed with the arm on the floor" ploy. Very interesting. (..)1975 The Return of the Pink Panther