What is Headroom?

Headroom definition and meaning on Dictionary terms:

Nautical. the clear space between two decks.
Also called headway.

  1. clear vertical space, as between the head and sill of a doorway, the ceiling and floor of a room, or the ceiling of a vehicular passageway and a vehicle roof, as to allow passage or comfortable occupancy: over 7.5 feet of headroom in the attic; a covered bridge with limited headroom.
  2. clear vertical space above one