sling has 5 distinct synonyms spread across 4 of its 9 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 highball with liquor and water with sugar and lemon or lime juice
a plaything consisting of a Y-shaped stick with elastic between the arms; used to propel small stones
Synonyms, antonyms and the broader and narrower relations for sling come from Princeton University’s WordNet. Full sources and licences.
a simple weapon consisting of a looped strap in which a projectile is whirled and then released
bandage to support an injured forearm; consisting of a wide triangular piece of cloth hanging from around the neck