Canon vs. cannon: how to use these words correctly

The short answer

Canon and cannon are pronounced alike but mean very different things. A canon is a rule, standard, or accepted collection of works, as in the literary canon. A cannon is a large mounted gun that fires heavy shot or shells. If you are talking about official church law or a set of respected books, you want canon, spelled with one n. If you mean artillery, choose cannon, with two n's. A single missing letter changes the whole meaning.

Where the words come from

Canon traces back through Latin to a Greek word meaning a measuring rod or rule, which explains why it still refers to standards and accepted works today. Church canon law and the literary canon both grew from this idea of a fixed, trusted measure that decisions could be checked against.

Cannon comes from an old Italian word for a large tube, related to the word for a reed or cane. Early gunpowder weapons were named for their tube-like barrels, and English borrowed the word directly for the large gun still called a cannon on ships and battlefields today.

What each word means

Canon comes from a word meaning rule or standard. In everyday use, it names a body of work accepted as genuine or essential, such as the Shakespeare canon studied in schools. It can also describe official church law, a musical technique built on repeated melodies, or a general principle, as when critics debate whether a novel belongs in the literary canon. A person who follows a strict personal canon is guided by a fixed set of beliefs.

Cannon refers to a heavy gun, traditionally mounted on wheels or a ship's deck, that fires solid shot or explosive shells. The word can also work as a verb, meaning to collide forcefully, as in the cyclist cannoned into a parked car. Modern military writing sometimes uses cannon for automatic weapons mounted on aircraft, and the plural can stay cannon or become cannons depending on the context.

Canon and cannon in a sentence

The museum's new exhibit explores the pirate ship's cannon and how sailors loaded it during battle. Literature teachers still argue over which contemporary novels deserve a place in the canon. During the reenactment, actors fired a replica cannon to mark the battle's opening moment. Editors decided the fan-written stories were not part of the official story canon, since only the original author's work counted as canon material.

• Cannon: weapon, artillery, or to collide
• Canon: rule, standard, or accepted works

Common mistakes to avoid

The mix-up usually happens because the words sound identical and both can act as nouns. Remember, not: the museum displayed an old book canon; the sentence needs cannon if it means the weapon. Likewise, not: the professor teaches the literary cannon; that sentence needs canon, since it refers to accepted texts, not guns. Spellcheck rarely flags either error, because both spellings are real words, so a careful proofread is the only reliable fix.

Remember it

Picture two n's in cannon like two wheels on a gun carriage, and one n in canon like a single rule everyone follows. If you can swap in the word gun and the sentence still makes sense, use cannon. If you can swap in the word rule or standard, use canon. Practicing with both example sentences a few times will make the correct spelling feel automatic.