What is the term for unauthorized use of a postage stamp?

The term for unauthorized use of a postage stamp is postage fraud. This concept encompasses activities where individuals use postage stamps improperly, such as reusing stamps or using stamps not intended for mailing certain items. Recognizing this term as correct highlights the legal implications associated with misusing postage, which can result in penalties under postal laws. Understanding postage fraud is essential for recognizing how such actions undermine the integrity of postal services and the financial system that supports them. The other terms provided in the options do not accurately describe this specific wrongdoing or are not commonly used in postal contexts.