Words of Art
The vocabulary or terminology of a particular art, science, or profession, particularly those expressions that are peculiar to it.
Though a society may share a common language, there are many specialized uses of words based on human activities. An examination of any profession, for example, will yield many expressions that are idiomatic or peculiar to it. For the person working within the profession, these become words of art, which usually convey a meaning much different from the normal use of these words, or which may be completely baffling to an outsider.
Because the law is based on the expression of language, it contains thousands of words of art. Many persons working outside the legal profession would recognize that "taking the Fifth" means that a person is asserting his or her protection against SELF-INCRIMINATION under the FIFTH AMENDMENT to the U.S. Constitution. However, very few persons would understand that an appellant is the party bringing an appeal, while a respondent is the party against whom the appeal is taken. Appellant and respondent are words of art.