[n] the act of concealing the existence of something by obstructing the view of it; "the cover concealed their guns from enemy aircraft"
[n] scenery used to block the audience's view of parts of the stage that should not be seen
[n] the blocking of one sensation resulting from the presence of another sensation; "he studied auditory masking by pure tones"
[adj] hiding from view; "speeding down the other lane beyond the masking truck"--T.H.White; "a masking piece is a flat or curtain that hides part of the stage from the audience"