The language is 'unfamiliar to' him. [=he does not know the language at all]
His 'unfamiliarity' with the language made the trip very challenging.
He gets nervous when he is in 'unfamiliar' surroundings.
(..) at the bottom of a check-- slide-- and then, ship that check off to its corresponding branch. Carl, for those of us who are unfamiliar with bank fraud you mind telling us what the hell you're talking about? The East Coast branches are numbered zero-one to zero-six. (..)2002 Catch Me If You Can