split has 21 distinct synonyms spread across 10 of its 18 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.
extending the legs at right angles to the trunk (one in front and the other in back)
a bottle containing half the usual amount
a promised or claimed share of loot or money
“he demanded his split before they disbanded”
a lengthwise crack in wood
“he inserted the wedge into a split in the log”
an old Croatian city on the Adriatic Sea
a dessert of sliced fruit and ice cream covered with whipped cream and cherries and nuts
(tenpin bowling) a divided formation of pins left standing after the first bowl
“he was winning until he got a split in the tenth frame”
an increase in the number of outstanding shares of a corporation without changing the shareholders' equity
“they announced a two-for-one split of the common stock”
having been divided; having the unity destroyed
“Congress...gave the impression of...a confusing sum of disconnected local forces”
1 of the 18 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for split.
Synonyms, antonyms and the broader and narrower relations for split come from Princeton University’s WordNet. Full sources and licences.
discontinue an association or relation; go different ways
“The business partners broke over a tax question”