obesity vs blubber

obesity and blubber both are nouns.

Word	Noun	Adjective	Verb	Adverb
obesity	Yes	No	No	No
blubber	Yes	No	Yes	No

As nouns, blubber is a hypernym of obesity; that is, blubber is a word with a broader meaning than obesity:

Other hypernyms of obesity include avoirdupois, fat, fatness.

obesity (noun)	blubber (noun)
more than average fatness	excess bodily weight
	an insulating layer of fat under the skin of whales and other large marine mammals; used as a source of oil

obesity (verb)	blubber (verb)
	cry or whine with snuffling
	utter while crying