ˈ ̷ ̷ˌ ̷ ̷ noun
1. : a space between the breech and bolt face of a firearm using rimless ammunition
2. : the space taken up by the cartridge rim in a firearm using rimmed ammunition
3. : a space left between the contents and the ends or closure of a drum, barrel, can, or bottle in order to allow for variations in fill or expansion of contents — called also outage