dash has 22 distinct synonyms spread across 9 of its 12 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 footrace run at top speed
“he is preparing for the 100-yard dash”
a punctuation mark (-) used between parts of a compound word or between the syllables of a word when the word is divided at the end of a line of text
the longer of the two telegraphic signals used in Morse code
Synonyms, antonyms and the broader and narrower relations for dash come from Princeton University’s WordNet. Full sources and licences.