croak vs break down

croak is a noun but break down is not a noun.

Word	Noun	Adjective	Verb	Adverb
croak	Yes	No	Yes	No
break down	No	No	Yes	No

croak (noun)	break down (noun)
a harsh hoarse utterance (as of a frog)

croak (verb)	break down (verb)
pass from physical life and lose all bodily attributes and functions necessary to sustain life	collapse due to fatigue, an illness, or a sudden attack
make complaining remarks or noises under one's breath	stop operating or functioning
utter a hoarse sound, like a raven	separate (substances) into constituent elements or parts
	make a mathematical, chemical, or grammatical analysis of; break down into components or essential features
	make ineffective
	cause to fall or collapse
	lose control of one's emotions
	fall apart