Final answer:
The British slang term for 'excellent' that is also a synonym for sorcerer is 'wizard'. The term has historical roots in magic and has been used to describe knowledgeable magic practitioners.
Step-by-step explanation:
The synonym for sorcerer that is also a British slang term meaning "excellent" is wizard. This term not only describes a skilled and knowledgeable practitioner of magic but has also evolved into slang in British English to express approval or excellence. The term wizard itself dates back to historical uses of magic and association with wise men or magi, encompassing a variety of practices, from the enchanting charms and spells to the deeper, more ritualistic aspects of magic as understood in various cultures. Historically, the word has undergone significant transformation, from the Persian term magus to the Roman interpretation that connected magic with those seen as outsiders and in some cases, the Roman law which punished certain magical acts. The Romans had various terms for those who practiced magic, such as hariolus for a fortune teller or prophet, and magus for a wise man or priest, showcasing how integral these concepts were to their culture, even as they sought to define and often ostracize the practices they considered unacceptable.