If a road, path, or route is impassable, it is impossible to travel over because it is blocked or in bad condition.
英漢詞典釋義
adj.
不能通行的,無法通過
The mud made the roads impassable.道路因為泥濘而無法通行。There was an impassable barrier between the white race and the one which they had reduced to slavery.在白色人種和被他們奴役的種族之間有一道不可逾越的障礙。