1.
Abbr. sig. One's name as written by oneself.
2. The act of signing one's name.
3. A distinctive mark, characteristic, or sound indicating identity: A surprise ending is the signature of an O. Henry short story.
4. Abbr. Sig., S. Medicine. The part of a physician's prescription containing directions to the patient.
5. Music. a. A sign used to indicate key. b. A sign used to indicate tempo.
6. Printing. a. A letter, number, or symbol placed at the bottom of the first page on each sheet of printed pages of a book as a guide to the proper sequence of the sheets in binding. b. A large sheet printed with four or a multiple of four pages that when folded becomes a section of the book.