straddle has 2 distinct synonyms spread across 2 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 noncommittal or equivocal position
a gymnastic exercise performed with a leg on either side of the parallel bars
the option to buy or sell a given stock (or stock index or commodity future) at a given price before a given date; consists of an equal number of put and call options
range or extend over; occupy a certain area
“The plants straddle the entire state”
1 of the 7 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 straddle.
Synonyms, antonyms and the broader and narrower relations for straddle come from Princeton University’s WordNet. Full sources and licences.