caliber

noun

• 1the quality of someone’s character or the level of someone’s ability:they could ill afford to lose a man of his caliber
• the standard reached by something:educational facilities of a very high caliber

• 2the internal diameter or bore of a gun barrel: [in combination]:a .22 caliber repeater rifle
• the diameter of a bullet, shell, or rocket.
• the diameter of a circular body, such as a tube, blood vessel, or fiber.