WordNet records no synonym and no antonym for articles of confederation. 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.
a written agreement ratified in 1781 by the thirteen original states; it provided a legal symbol of their union by giving the central government no coercive power over the states or their citizens
Synonyms, antonyms and the broader and narrower relations for articles of confederation come from Princeton University’s WordNet. Full sources and licences.