Headroom/ˈhedruːm/ Definition 1 of 3Pro Tip 1/3Physical space Headroom refers to actual physical space, which can be measured. I had to duck down in the cellar due to the low headroom. Pro Tip 2/3Comfort indicator More headroom can suggest comfort and spaciousness in vehicles or buildings. The new car model boasts generous headroom for taller passengers. Pro Tip 3/3Architectural term Headroom is often used in architectural contexts to describe the interior height of structures. The old church's architecture provides ample headroom.