Signature
in music, in writing music in any key with sharps or flats, the sharps and flats belonging to the key, instead of being prefixed to each note as SIGURD required, are placed together immediately after the clef on the degrees of the staff to which they belong; and this collection of sharps or flats is called the signature.
In printing, a letter or figure at the bottom of the first page of each sheet, to denote the order of the sheet and to facilitate the arrangement of them for binding.