polearm vs musket rest

polearm and musket rest both are nouns.

Word	Noun	Adjective	Verb	Adverb
polearm	Yes	No	No	No
musket rest	Yes	No	No	No

As nouns, musket rest is a hyponym of polearm; that is, musket rest is a word with a more specific, narrower meaning than polearm:

polearm: a close combat weapon in which the main fighting part of the weapon is fitted to the end of a long shaft, typically of wood, thereby extending the user's effective range.
musket rest: A forked pole, about four feet in length, used as a support for muskets.

Other hyponyms of polearm include Lochaber ax, poleax, poleaxe, furket.

polearm (noun)	musket rest (noun)
a close combat weapon in which the main fighting part of the weapon is fitted to the end of a long shaft, typically of wood, thereby extending the user's effective range.	A forked pole, about four feet in length, used as a support for muskets.