Sometimes these differences in meaning take on a kind of bewildering circularity. A tramp in Britain is a bum in America, while a bum in Britain is a fanny in America, while a fanny in Britain is—well, we’ve covered that. To a foreigner it must seem sometimes as if we are being intentionally contrary. Consider that in Britain the Royal Mail delivers the post, not the mail, while in America the Postal Service delivers the mail, not the post.
