A more thorough explanation:

Definition: To damage or ruin something by removing or altering its original appearance or features.

Examples:

• Someone defaced the statue in the park by spray painting it.
• The graffiti artist defaced the wall with their tag.
• The vandals defaced the school's bathroom stalls with vulgar language.

The examples illustrate how defacing something means to damage or ruin it by altering its original appearance. In the first example, the statue was defaced by spray painting it, which changed its original appearance. In the second example, the wall was defaced by the graffiti artist's tag, which altered its original appearance. In the third example, the bathroom stalls were defaced by the vandals writing vulgar language on them, which damaged their original appearance.