cannon vs lower cannon

cannon and lower cannon both are nouns.

Word	Noun	Adjective	Verb	Adverb
cannon	Yes	No	Yes	No
lower cannon	Yes	No	No	No

As nouns, lower cannon is a hyponym of cannon; that is, lower cannon is a word with a more specific, narrower meaning than cannon:

Other hyponyms of cannon include rerebrace, upper cannon, vambrace.

cannon (noun)	lower cannon (noun)
a shot in billiards in which the cue ball contacts one object ball and then the other	cannon of plate armor protecting the forearm
lower part of the leg extending from the hock to the fetlock in hoofed mammals
a large artillery gun that is usually on wheels
heavy automatic gun fired from an airplane
(Middle Ages) a cylindrical piece of armor plate to protect the arm
heavy gun fired from a tank

cannon (verb)	lower cannon (verb)
fire a cannon
make a cannon