Defacement

noun

1. An act of defacing; an instance of visibly marring or disfiguring something.

   "Some consider the defacement of the Sphinx to be the most egregious crime of Napolean's campaigns."

2. An act of voiding or devaluing; nullification of the face value.

   "The soldiers found a variety of creative uses for their payment scrip after its defacement to scrap paper; some used it as toilet paper."

3. (vexillology) A symbol added to a flag or coat of arms to change it or make it different from another.