ludi saeculares has 1 distinct synonym 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.
the centennial rites and games of ancient Rome that marked the commencement of a new generation (100 years representing the longest life in a generation); observances may have begun as early as the 5th century BC and lasted well into the Christian era
Synonyms, antonyms and the broader and narrower relations for ludi saeculares come from Princeton University’s WordNet. Full sources and licences.