croak vs asphyxiate

croak is a noun but asphyxiate is not a noun.

Word	Noun	Adjective	Verb	Adverb
croak	Yes	No	Yes	No
asphyxiate	No	No	Yes	No

As verbs, asphyxiate is a hyponym of croak; that is, asphyxiate is a word with a more specific, narrower meaning than croak:

croak: pass from physical life and lose all bodily attributes and functions necessary to sustain life
asphyxiate: be asphyxiated; die from lack of oxygen

Other hyponyms of croak include abort, stifle, suffocate, buy it, pip out, drown, predecease, famish, starve, fall, succumb, yield.

croak (noun)	asphyxiate (noun)
a harsh hoarse utterance (as of a frog)

croak (verb)	asphyxiate (verb)
pass from physical life and lose all bodily attributes and functions necessary to sustain life	be asphyxiated; die from lack of oxygen
make complaining remarks or noises under one's breath	deprive of oxygen and prevent from breathing
utter a hoarse sound, like a raven	impair the respiration of or obstruct the air passage of