Definition of white out in US English:

white out

phrasal verb

  • 1(of vision) become impaired by exposure to sudden bright light.

    • ‘My head had started to spin again, and my vision almost whited out.’
    • ‘He tried to raise his head, and his sight whited out entirely.’
    1. 1.1 (of a person) lose color vision as a prelude to losing consciousness.
      • ‘I bolted for the door and whited out as I hit the street.’