white as a sheet/ghost
*white as a sheetand *white as a ghost; *white as snow; *white as the driven snow
[of someone] extremely pale, as if frightened. (*Also: as ~.) Marilyn turned as white as a sheet when the policeman told her that her son had been in a car wreck. Did something scare you? You're white as a sheet! Jane made up the bed with her best linen sheets, which are always as white as snow. We have a new kitten whose fur is white as the driven snow.
white as a sheet
Very pale in the face, as in She was white as a sheet after that near encounter. This simile, dating from about 1600, survives despite the fact that bedsheets now come in all colors.
white as a sheetor
white as a ghost
If someone looks as white as a sheet or as white as a ghost, they look very pale because they are frightened, shocked or ill. When I saw him his face was as white as a sheet and he was crying. She was as white as a ghost and trembling all over.