Definition of lightless in US English:

lightless

adjective

  • See light

    • ‘The path we followed was merely a space between two stone walls, dank and lightless.’
    • ‘After midnight the storm finally blew itself out, and the lightless convoy moved out.’
    • ‘They were not alone in enjoying this subterranean existence because Bermuda's caves support a diverse fauna specially adapted to a lightless existence.’
    • ‘As an added bonus, the keyboard seems to light up, which I envision will be a boon to struggling typists working in windowless, lightless spaces.’
    • ‘Satisfied, Haywood led her out of the plain, dark room, and into the lightless hallways.’