What does "headspace" mean?

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

What is a synonym for "headspace"?

Common synonyms include: brainspace, headroom, innerworld, mindscape, state of mind, ullage.

//ˈhɛdspeɪs// noun, verb, slang

noun, verb, slang ·Moderate ·College level

Noun

1
The space between the top of the contents of a container (such as a jar) and its seal (such as a lid). countable, uncountable
"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
the volume left at the top of a filled container (bottle or jar or tin) before sealing wordnet
3
One's capacity for mental activity modeled as a physical space with limits; one's mental state or state of mind. countable, informal, uncountable
"Meronym: mindshare"
4
Time and opportunity for reflection and thinking. countable, informal, uncountable
"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
The gap between the face of the bolt and the stopping surface for the cartridge. countable, uncountable

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6
The gas phase in contact and in equilibrium with a nonvolatile liquid in a sample. countable, uncountable
7
A place within a person (singlet or multiple) that they can visit or inhabit. countable, uncountable

Verb

"Mary told Tom that she wasn't in the right headspace to have a relationship with him."

From head + space.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.