whiteout has 2 distinct synonyms spread across 2 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.
an arctic atmospheric condition with clouds over snow produce a uniform whiteness and objects are difficult to see; occurs when the light reflected off the snow equals the light coming through the clouds
Synonyms, antonyms and the broader and narrower relations for whiteout come from Princeton University’s WordNet. Full sources and licences.