headspace

noun

1. (countable, uncountable)The space between the top of the contents of a container (such as a jar) and its seal (such as a lid).

   “Control of headspace is important for economic and technical reasons. Underfilling will contravene Weights and Measures legislation and may cause rusting in the headspace […]”

2. (countable, informal, uncountable)One's capacity for mental activity modeled as a physical space with limits.

   “Meronym: mindshare”

   “It's like, I need to clear my headspace but I can't do that with him around because he's just ego, you know? He dumps on me. So that's it.”

   “Harry looked pained. "Please don't let me out of here. I really don't have the headspace for the moral implications of any of that right now. But as I was saying," he did so hate to be interrupted, it was the lecturing academic in him, "if I wanted a third girlfriend, I'd choose from the pool of non-murderers."”

3. (countable, uncountable)One's mental state or state of mind.

   “Many of us, as gays, have been in the same headspace as Maurice: longing, lonely, and scared.”

4. (countable, informal, uncountable)A time and opportunity for reflection and thinking.

   “As a business owner, a truly effective business owner that is building a profitable business machine, you need headspace, thinking time, planning time, brainstorming time, education time, decision making time, questioning time and more thinking time.”

5. (countable, uncountable)The gap between the face of the bolt and the stopping surface for the cartridge.
6. (countable, uncountable)The gas phase in contact and in equilibrium with a nonvolatile liquid in a sample.
7. (countable, uncountable)A place within a person (singlet or multiple) that they can visit or inhabit.

verb

1. (transitive)To occupy a headspace.