[ grə'fi:ti ]
■ plural noun ( sing. graffito -təʊ ) [treated as sing. or plural ] unauthorized writing or drawings on a surface in a public place.
■ verb write or draw ~ on.
Derivatives
~st noun
Origin
C19: from Ital., from graffio 'a scratch'.
Usage
In Italian ~ is a plural noun and its singular form is graffito . In modern English, ~ is used as a plural in some specialist fields such as archaeology but in general use it is acceptable to treat it as if it were a mass noun (with a singular verb), similar to a word like writing .