1. Any inscriptions left on walls, usually without the approval of local authorities.
2. Inscriptions, figure drawings, etc., found on the walls of ancient sepulchers or ruins, as in the Catacombs, or at Pompeii.
Inscriptions or drawings carved, scratched, or drawn on public surfaces, such as walls, fences, or public-transport vehicles.
Tagging is the act of writing an individual logo on surfaces with spray paint or large felt-tip pens.
The term “graffiti” is derived from a traditional technique in Italian art (sgraffito) of scratching a design in the thin white plaster on a wall.

A software application developed by Palm to allow handwriting recognition on personal digital assistants (PDAs). Graffiti contains preprogrammed shapes for each letter, which users of the application must match as closely as possible when writing. Text is written directly onto the PDA’s display screen using a stylus. The Graffiti application then passes the translated letter to the PDA’s application.

To draw graffiti on; to deface with graffiti