The noun mockery means ridicule or making a fool out of someone. Mockery of your history teacher is unwise just before she grades your mid-term exams.
Mockery is making fun of or mocking someone or something. The act of mockery often involves copying someone's behavior or speech, making it look absurd, like a parody. For example, comedians often get laughs with mockery, by pretending to be famous politicians and exaggerating the way they talk or gesture. The expression "to make a mockery of" means to make something appear foolish or absurd, even if that’s not the intent — like a trial that “makes a mockery of justice.”