headspace

Short definition from Wiktionary

Noun

1. 1
   The space between the top of the contents of a container (such as a jar) and its seal (such as a lid).
2. 2
   One's capacity for mental activity modeled as a physical space with limits; one's mental state or state of mind.
3. 3
   Time and opportunity for reflection and thinking.
4. 4
   The gap between the face of the bolt and the stopping surface for the cartridge.
5. 5
   The gas phase in contact and in equilibrium with a nonvolatile liquid in a sample.
6. 6
   A place within a person (singlet or multiple) that they can visit or inhabit.

Verb

1. 1
   To occupy a headspace.