Homonym: caliber (Quality)
Caliber refers to the internal diameter or bore of a firearm's barrel, typically measured in millimeters or inches. It is an important specification that helps determine the size of the ammunition that can be used in the firearm. For example, a 9mm handgun uses bullets that are 9 millimeters in diameter, while a 0.45 caliber pistol uses .45-inch diameter bullets.
In addition to firearms, the term caliber can also describe the quality or degree of excellence of a person or thing. For instance, one might refer to a caliber of leadership when discussing the effectiveness of a leader, indicating their skills and abilities in guiding others.