From WordNet (r) 2.0 (August 2003) [wn]:
graffiti
n : a rude decoration inscribed on rocks or walls [syn:
graffito]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Graffiti \Graf*fi"ti\, n. pl. [It., pl. of graffito scratched]
1. Inscriptions, figure drawings, etc., found on the walls of
ancient sepulchers or ruins, as in the Catacombs, or at
Pompeii.
[1913 Webster]
2. any writings or drawings on a surface in a public place,
placed there without authorization of the owner of the
object on which it is written. Such graffiti are usually
unwelcome, and are considered as form of vandalism.
[PJC]
From The Free On-line Dictionary of Computing (19 Sep 2003) [foldoc]:
Graffiti
Handwriting recognition software for the Newton and Zoomer
which recognises symbols that aren't necessarily letters.
This gives greater speed and accuracy. It was written by
Berkeley Softworks.
(1995-01-24)