legal-terms definition
Is there a term denoting definitions that are contrary to a term&#39;s plain meaning?
<p>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, <a href="https://www.law.cornell.edu/uscode/text/52/30121" rel="nofollow noreferrer">52 USC 30121</a> defines "foreign national" to exclude permanent resident aliens despite the fact that such a person does not have US nationality, and the <a href="https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02016R0399-20170407" rel="nofollow noreferrer">Schengen Borders Code</a> 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."</p>

<p>As a hypothetical example, consider a definition of "grape" that excludes concord grapes.</p>

<p>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.</p>

<p>Most of your examples don't seem to be so much self-contradictory, as limited to a subset of the obvious meaning for purposes of a particular law. When a term has a specific meaning within a particular field or context, it is often called a "term of art". For example "Fair use" is a term of art in US Copyright law, and "Under color of law" is a term of art in US civil rights law. "Standing" is a term of art in most common-law jurisdictions.  But a term of art is usually somewhat broadly understood, and is not limited to one particular law or section of law. I would just call such a thing a "specially defined term" or just say "Q as defined for purposes of the XYZ law". </p>
