electric shock has 2 distinct synonyms spread across 1 of its 3 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.
the use of electricity to administer punishment or torture
“they used cattle prods to administer electric shocks”
trauma caused by the passage of electric current through the body (as from contact with high voltage lines or being struck by lightning); usually involves burns and abnormal heart rhythm and unconsciousness
a reflex response to the passage of electric current through the body
“subjects received a small electric shock when they made the wrong response”
Synonyms, antonyms and the broader and narrower relations for electric shock come from Princeton University’s WordNet. Full sources and licences.