lobby group has 7 distinct synonyms spread across 1 of its 1 sense. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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 interest group that tries to influence legislators or bureaucrats to act in their favor, typically through lobbying
Synonyms, antonyms and the broader and narrower relations for lobby group come from Princeton University’s WordNet. Full sources and licences.