spill has 13 distinct synonyms spread across 8 of its 10 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.
pour out in drops or small quantities or as if in drops or small quantities
“shed tears”
reduce the pressure of wind on (a sail)
liquid that is spilled
“clean up the spills”
Synonyms, antonyms and the broader and narrower relations for spill come from Princeton University’s WordNet. Full sources and licences.