sig·na·ture 
(sĭgnə-chər)
(sĭgnə-chər)n.
1.
a. One's name as written by oneself.
b. The act of signing one's name.
c. See e-signature.
2. A distinctive mark, characteristic, or sound indicating identity: A surprise ending is the signature of an O. Henry short story.
3. Medicine The part of a physician's prescription containing directions to the patient.
4. Music
a. A sign used to indicate key.
b. A sign used to indicate tempo.
5. 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.
6. See chemical signature.
[French, from Old French, from Medieval Latin signātūra, from Latin signātus, past participle of signāre, to mark, from signum, sign; see SIGN.]