Refers to a large mounted gun, often historical or military. The cross-reference to カノン suggests a possible alternative spelling, but キャノン is the standard katakana form for 'cannon'.
See also: カノン
An old cannon is placed in front of the castle.
carom; cannon (billiards)
In billiards, a shot where the cue ball strikes two object balls in succession. The cross-reference to キャロム indicates a related term, but キャノン is also used for this billiard shot.
See also: キャロム
The castle's soldiers fired the cannon and drove off the enemy.
He made a brilliant carom.
He beautifully made a difficult carom shot.
カノン can mean the same 'cannon' as キャノン but more often refers to a musical canon or a rule/standard, so context is essential to distinguish them.
gate; doorway · school (of thought); branch of learning · phylum; division (biology) · counter for cannons
Borrowed from English 'cannon'. The billiards sense is also from English, where 'cannon' is a British term for a carom shot.