Long ago, the word for a big gun and an accepted body of rules was the same, but today, you have to distinguish between "cannon" and "canon."
As a fiction fan, I’m always amused when people write about how a new book in a series or a new movie in a franchise deviates from cannon because a cannon is a large, heavy gun.
These readers and viewers are actually annoyed because the new material deviates from canon: an accepted body or collection of rules or principles. In this case, canon is the collection of rules, ideas, and history that govern the imaginary world, but “canon” is also used to describe a collection of official documents (the books of the Bible), authentic works of an author (Shakespeare’s canon), and a religious or secular law.
“Canonical” is the adjective. For example, you could talk about the canonical books of the Bible or the canonical writers of the seventeenth century.
There’s also a verb form of the word. Saints are canonized, for example.
In the fifteenth century and earlier, “cannon” was also spelled “canon,” but you live in the twenty-first century, so stick with “cannon,” with two N’s, for the weapon.
How to Remember the Spelling of 'Canon' and 'Cannon'
Multiple listeners, including Waldo Berg and Carol Einarsson, suggested a great memory trick: Remember that “cannon,” the weapon, has more N’s by thinking of them as ammunition, cannonballs. A gun or cannon fires the same kind of ammunition over and over, kind of like the repeated N’s in the word. If you’re in a battle using a cannon, you want as much ammunition as possible. More N’s equals more cannonballs, so “cannon,” the weapon, is spelled with two N’s in the middle instead of one.
Examples of ‘Cannon’
Well, sir, you more than meet every one of this state's requirements to box, wrestle or be shot out of a cannon. ― The Simpsons
We have rail guns and cannons. They apparently have a full complement of self-guided missiles. ― Dark Matter
Don't give yourselves to brutes, men who despise you, enslave you; who regiment your lives, tell you what to do, what to think and what to feel! Who drill you, diet you, treat you like cattle, use you as cannon fodder. ― Charlie Chaplin
Examples of ‘Canon’
Is that how you see it? Us versus them? Ms. Rubirosa is conducting herself within the bounds of the canon of ethics, and zealously representing her client to the best of her abilities. That's what she's expected to do, whether that client is a criminal defendant or the people of the state of New York. ― Law & Order
Where would you rate "Pink Cadillac" in the Eastwood canon? ― Psych
To be really great in little things, to be truly noble and heroic in the insipid details of everyday life, is a virtue so rare as to be worthy of canonization. ― Harriet Beecher Stowe
Image courtesy of Shutterstock.