stiffening vs natural process

stiffening and natural process both are nouns.

Word	Noun	Adjective	Verb	Adverb
stiffening	Yes	No	No	No
natural process	Yes	No	No	No

As nouns, natural process is a hypernym of stiffening; that is, natural process is a word with a broader meaning than stiffening:

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

Other hypernyms of stiffening include action, activity, natural action.

stiffening (noun)	natural process (noun)
the act of becoming stiff	a process existing in or produced by nature (rather than by the intent of human beings)
the process of becoming stiff or rigid