graffito

Etymology
Borrowed from.

Noun

 * 1)  An informal inscription, as by a worker or vandal.
 * 2)  A single instance of graffiti in the art/vandalism sense.

Usage notes
Outside of archaeology, graffiti or “a piece of graffiti” is used for the singular. As graffiti is borrowed from a plural form, prescriptivists consider singular use of graffiti incorrect: compare data/datum. The use of "graffiti" in contemporary art is a synonym to "Tags-Throw-ups-Pieces", TTP in short.

Noun

 * 1) graffiti