labour has 20 distinct synonyms spread across 7 of its 7 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.
a social class comprising those who do manual labor or work for wages
“there is a shortage of skilled labor in this field”
concluding state of pregnancy; from the onset of contractions to the birth of a child
“she was in labor for six hours”
a political party formed in Great Britain in 1900; characterized by the promotion of labor's interests and formerly the socialization of key industries
Synonyms, antonyms and the broader and narrower relations for labour come from Princeton University’s WordNet. Full sources and licences.