breakdown vs dud

breakdown and dud both are nouns.

Word	Noun	Adjective	Verb	Adverb
breakdown	Yes	No	No	No
dud	Yes	Yes	No	No

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

Other hyponyms of breakdown include brake failure, engine failure, misfire, outage, power failure, power outage, fault.

breakdown (noun)	dud (noun)
the act of disrupting an established order so it fails to continue	an event that fails badly or is totally ineffectual
an analysis into mutually exclusive categories	an explosion that fails to occur
a cessation of normal operation	someone who is unsuccessful
(biology) the process of decay caused by bacterial or fungal action
(chemistry) separation of a substance into two or more substances that may differ from each other and from the original substance
a mental or physical breakdown

breakdown (adjective)	dud (adjective)
	failing to detonate; especially not charged with an active explosive