What does "jargon" refer to?

The term "jargon" specifically denotes the specialized language used by individuals within a particular profession or field, which can include unique terms, acronyms, and expressions that may not be easily understood by outsiders. This type of language serves to convey complex concepts and ideas more efficiently among professionals who share a common understanding of the terminology. For instance, medical jargon could include terms like "hypertension" or "benign," which have specific meanings to healthcare providers but might confuse those not in the field.

In contrast, the other options describe different types of language. Common terminology refers to words that are understood by the general public, slang involves informal and often playful language, and historical terms pertain to language used in earlier periods, which could include archaic expressions or terminology found in literature from those times. These distinctions highlight why the correct answer focuses on technical language for specific groups, while the other options do not align with that definition.