聘书 (pìn shū) is a formal written document issued by an organization or institution to officially appoint someone to a position—most commonly for academic, professional, or diplomatic roles. The character 聘 (pìn) means 'to hire' or 'to appoint', often with connotations of respect and formality, while 书 (shū) means 'document' or 'letter'. Together, they literally mean 'appointment letter' or 'letter of appointment'.

This term is used in official, institutional contexts—not for casual jobs or everyday hiring. It typically carries legal or ceremonial weight, such as when a university appoints a visiting professor, a company names a new director, or a government agency assigns a representative. Unlike informal job offers, a 聘书 is usually printed on official letterhead, signed by authorized personnel, and may be presented in person during a formal ceremony. It reflects mutual commitment and is often accompanied by a contract outlining duties and terms.