headspace

head space |ˈhedˌspās ˈhɛdspeɪs | ▶noun the unfilled space above the contents of a closed container.

headspace

head |space ▶noun [ mass noun ] 1 the air or empty space left above the contents in a sealed container. 2 informal the notional space occupied by a person's mind: to play, you enter the headspace of a female bounty hunter.