cal·i·bre (k?l??-b?r)n. Chiefly British Variant of caliber.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.calibre (?kæl?b?) or calibern1. (Firearms, Gunnery, Ordnance & Artillery) the diameter of a cylindrical body, esp the internal diameter of a tube or the bore of a firearm2. (Firearms, Gunnery, Ordnance & Artillery) the diameter of a shell or bullet3. ability; distinction: a musician of high calibre. 4. personal character: a man of high calibre. [C16: from Old French, from Italian calibro, from Arabic q?lib shoemaker’s last, mould] ?calibred, ?calibered adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014