revolver vs side arm

revolver and side arm both are nouns.

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

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

revolver: a pistol with a revolving cylinder (usually having six chambers for bullets)
side arm: a firearm that is held and fired with one hand

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

revolver (noun)	side arm (noun)
a pistol with a revolving cylinder (usually having six chambers for bullets)	a firearm that is held and fired with one hand
a door consisting of four orthogonal partitions that rotate about a central pivot; a door designed to equalize the air pressure in tall buildings