Calibre

Calibre, pronounced with the stress on the first syllable 'KAL-ib-er', IPA: /ˈkæl ə(or ɪ)b ə^r/ (spelled 'caliber' in American English, and stressed on the second syllable, 'kel-EEB-er', /kæl ˈiːb ə^r) is a measurement used for firearms and their projectiles. It is, strictly speaking, the diameter of a cannon-ball, or other ammunition, and thus the diameter of the inside of the gun-barrel through which the projectile must pass, with a tight fit. (It is thus generally synonymous with bore, as used by (shot)gun-makers.) More loosely, it was used in the early Gunpowder period for the 'weight of shot' [of a ball of the appropriate size cast in lead]. Sometimes the length of a gun-barrel was expressed as a given number of calibres - that is, as a multiple of the barrel's internal diameter.

• Figuratively calibre is used to mean 'quality'. We can talk of an employee of high calibre, meaning 'of good quality'.