Legislation sometimes defines a term so that it is contradictory to its plain meaning, or contradictory to the term's meaning in another context. For example, 52 USC 30121 defines "foreign national" to exclude permanent resident aliens despite the fact that such a person does not have US nationality, and the Schengen Borders Code defines "third-country national" to exclude, among others, "third-country nationals who are members of the family of a Union citizen exercising his or her right to free movement to whom Directive 2004/38/EC of the European Parliament and of the Council applies."
As a hypothetical example, consider a definition of "grape" that excludes concord grapes.
Is there a term that describes such a definition? I am thinking of calling it a "self-contradictory" definition, but that doesn't seem quite right.