trouble has 23 distinct synonyms spread across 9 of its 11 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.
an event causing distress or pain
“what is the trouble?”
an unwanted pregnancy
“he got several girls in trouble”
Synonyms, antonyms and the broader and narrower relations for trouble come from Princeton University’s WordNet. Full sources and licences.
to cause inconvenience or discomfort to
“Sorry to trouble you, but...”
take the trouble to do something; concern oneself
“He did not trouble to call his mother on her birthday”