rigidification vs activity

rigidification and activity both are nouns.

Word	Noun	Adjective	Verb	Adverb
rigidification	Yes	No	No	No
activity	Yes	No	No	No

As nouns, activity is a hypernym of rigidification; that is, activity is a word with a broader meaning than rigidification:

rigidification: the process of becoming stiff or rigid
activity: a process existing in or produced by nature (rather than by the intent of human beings)

Other hypernyms of rigidification include action, natural action, natural process.

rigidification (noun)	activity (noun)
the process of becoming stiff or rigid	any specific behavior
	the trait of being active; moving or acting rapidly and energetically
	an organic process that takes place in the body
	a process existing in or produced by nature (rather than by the intent of human beings)
	the state of being active
	(chemistry) the capacity of a substance to take part in a chemical reaction