WordNet records no synonym and no antonym for joint resolution. 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 resolution passed by both houses of Congress which becomes legally binding when signed by the Chief Executive (or passed over the Chief Executive's veto)
Synonyms, antonyms and the broader and narrower relations for joint resolution come from Princeton University’s WordNet. Full sources and licences.