Used attributively before another noun to specify the diameter of a firearm barrel or the size/quality of something, e.g., “.30-caliber rifle,” “high-caliber work.”
Definitions
Attributive: Relating to or denoting the diameter of a firearm barrel or the size of ammunition (or, figuratively, the quality of something) when placed before another noun.
Officers seized a 9 mm caliber handgun during the raid.