WordNet records no synonym and no antonym for fifth amendment. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
an amendment to the Constitution of the United States that imposes restrictions on the government's prosecution of persons accused of crimes; mandates due process of law and prohibits self-incrimination and double jeopardy; requires just compensation if private property is taken for public use
Synonyms, antonyms and the broader and narrower relations for fifth amendment come from Princeton University’s WordNet. Full sources and licences.