bullet vs dumdum

bullet and dumdum both are nouns.

Word	Noun	Adjective	Verb	Adverb
bullet	Yes	No	No	No
dumdum	Yes	No	No	No

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

bullet: a projectile that is fired from a gun
dumdum: a soft-nosed small-arms bullet that expands when it hits a target and causes a gaping wound

Other hyponyms of bullet include dumdum bullet, full metal jacket, rifle ball, rubber bullet.

bullet (noun)	dumdum (noun)
(baseball) a pitch thrown with maximum velocity	a soft-nosed small-arms bullet that expands when it hits a target and causes a gaping wound
a projectile that is fired from a gun
a high-speed passenger train