means A correction fluid painted over an error on paper, or by extension a blizzard so dense the world dissolves into featureless white.

from A plain English compound of "white" plus "out," meaning to obliterate by covering in white — first used for blinding snow conditions, then adopted in the mid-20th century for the little bottles of correction fluid that paint over typing mistakes. "White" traces back through Old English "hwit" to a Germanic root tied to brightness, a cousin of words meaning to gleam or shine.