What is letter all about?

One who lets or permits; one who lets anything for hire., One who retards or hinders., A mark or character used as the representative of a sound, or of an articulation of the human organs of speech; a first element of written language., A written or printed communication; a message expressed in intelligible characters on something adapted to conveyance, as paper, parchment, etc.; an epistle., A writing; an inscription., Verbal expression; literal statement or meaning; exact signification or requirement., A single type; type, collectively; a style of type., Learning; erudition; as, a man of letters., A letter; an epistle., To impress with letters; to mark with letters or Words; as, a book gilt and lettered.