What efers to the language of a specialized type usually dealing with narrow area study or knowledge?

The language of a specialized type usually dealing with a narrow area of study or knowledge is called jargon.

Here's why:

* Jargon is a specialized vocabulary used by people in a particular profession or group. This vocabulary often includes technical terms, abbreviations, and slang that are not commonly understood by people outside that group.

* Technical language is a similar term, but it specifically refers to the language used in a particular field of study or work. This language is often more formal and precise than jargon.

* Slang is a type of informal language that is used by a particular group of people. It can be specific to a particular region, age group, or profession.

While all three terms describe specialized language, jargon is the most general term and encompasses both technical language and slang.