headspace /ˈhɛdspeɪs/noun 7verb 1forms 3 noun7 •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 […] — 1997 •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. — 1971 •(informal) One's capacity for mental activity modeled as a physical space with limits.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. — 1996 •(informal) A time and opportunity for reflection and thinking. •The gas phase in contact and in equilibrium with a nonvolatile liquid in a sample. •The gap between the face of the bolt and the stopping surface for the cartridge. •A place within a person (singlet or multiple) that they can visit or inhabit. verb1 •To occupy a headspace. formsheadspaced · headspacing · headspaces