differencing a flag by adding something to it, such as a charge, a badge, or writing Used especially on colonial flags Note that this term does not have the usual meaning of "vandalizing" when used in vexillology
One-and-twenty worn and defaced shillings, however, were considered as equivalent to a guinea, which perhaps, indeed, was worn and defaced too, but seldom so much so.
To destroy or mar the face or external appearance of; to disfigure; to injure, spoil, or mar, by effacing or obliterating important features or portions of; as, to deface a monument; to deface an edifice; to deface writing; to deface a note, deed, or bond; to deface a record
If someone defaces something such as a wall or a notice, they spoil it by writing or drawing things on it. It's illegal to deface banknotes. to spoil the surface or appearance of something, especially by writing on it or breaking it