An unoccupied area or volume.
Vacuum; a space containing nothing at all
An unoccupied space where something may be stored
A feeling of longing for someone or something that is gone; a sense of a thing's absence.
The vertical clearance above someone's head, as in a tunnel, doorway etc.
The ability of a system to reproduce loud sounds free of distortion; dynamic headroom.
The vertical measurement, top to bottom, for example for clearance under a bridge.
The distance between the actual performance of an algorithm and its maximum possible performance.