blackout has 4 distinct synonyms spread across 2 of its 5 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 suspension of radio or tv broadcasting
Synonyms, antonyms and the broader and narrower relations for blackout come from Princeton University’s WordNet. Full sources and licences.
the failure of electric power for a general region
a momentary loss of consciousness
partial or total loss of memory
“he has a total blackout for events of the evening”