How do you spell Calibre

Available Definitions:
1)  n. - The diameter of the bore, as a cannon or other firearm, or of any tube; or the weight or size of the projectile which a firearm will carry; as, an 8 inch gun, a 12-pounder, a 44 caliber.
2)  n. - The diameter of round or cylindrical body, as of a bullet or column.
3)  n. - Fig.: Capacity or compass of mind.