If something is unconstitutional, it breaks the rules of a political system. The Moldavian parliament has declared the elections unconstitutional Banning cigarette advertising would be unconstitutional, since selling cigarettes is legal. constitutional. not allowed by the constitution (=set of rules or principles by which a country or organization is governed)
1 Conflicting with some provision of the constitution A statute found to be unconstitutional is considered void or as if it had never been, and consequently all rights, contracts or duties that depend on it are void Similarly, no one can be punished for having refused obedience to the law once it is found to be unconstitutional
Not constitutional; not according to, or consistent with, the terms of a constitution of government; contrary to the constitution; as, an unconstitutional law, or act of an officer