peacekeeper vs side arm

peacekeeper and side arm both are nouns.

Word	Noun	Adjective	Verb	Adverb
peacekeeper	Yes	No	No	No
side arm	Yes	No	No	No

As nouns, side arm is a hypernym of peacekeeper; that is, side arm is a word with a broader meaning than peacekeeper:

Other hypernyms of peacekeeper include handgun, pistol, shooting iron.

peacekeeper (noun)	side arm (noun)
the pistol of a law officer in the old West	a firearm that is held and fired with one hand
someone who keeps peace
a member of a military force that is assigned (often with international sanction) to preserve peace in a trouble area