laziness has 3 distinct synonyms spread across 2 of its 3 senses. 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.
inactivity resulting from a dislike of work
relaxed and easy activity
“the laziness of the day helped her to relax”
Synonyms, antonyms and the broader and narrower relations for laziness come from Princeton University’s WordNet. Full sources and licences.
apathy and inactivity in the practice of virtue (personified as one of the deadly sins)