Which word describes the act of maligning or defaming someone?

The term "vilify" precisely conveys the act of maligning or defaming someone. To vilify means to speak or write about someone in an abusively disparaging manner, effectively tarnishing their reputation through negative and harmful statements. This word is often used in contexts where someone seeks to damage another's character or standing, particularly through slander or libel.

The other choices do not carry the same meaning. "Surreptitious" refers to actions done secretly or stealthily, often to avoid notice, which does not relate to maligning someone. "Transcendent" describes something that goes beyond ordinary limits; it is associated with a state of being that surpasses typical experiences, which is unrelated to defamation. "Xerography" pertains to a method of copying documents using light and electrostatic charges, having no connection to the idea of harming someone's reputation. Each of these terms serves specific meanings that do not overlap with the concept of vilifying, making "vilify" the clear and correct choice.