masking has 4 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.
the act of concealing the existence of something by obstructing the view of it
“the cover concealed their guns from enemy aircraft”
the blocking of one sensation resulting from the presence of another sensation
“he studied auditory masking by pure tones”
Synonyms, antonyms and the broader and narrower relations for masking come from Princeton University’s WordNet. Full sources and licences.
scenery used to block the audience's view of parts of the stage that should not be seen