unceasingly has 5 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.
with unflagging resolve
“dance inspires him ceaselessly to strive higher and higher toward the shining pinnacle of perfection that is the goal of every artiste”
Synonyms, antonyms and the broader and narrower relations for unceasingly come from Princeton University’s WordNet. Full sources and licences.