autograph

Short definition from Wiktionary

Noun

1. 1
   A person’s own handwriting, especially the signature of a famous or admired person.
2. 2
   A person's signature used as a mark of formal approval.
3. 3
   A manuscript in the author’s handwriting.

Adjective

1. 1
   Written in the author’s own handwriting.
2. 2
   Made by the artist himself or herself; authentic.

Verb

1. 1
   To sign, or write one’s name or signature on a book, etc.
2. 2
   To write something in one's own handwriting.