inflexible vs stiff

inflexible is not a noun while stiff is a noun.

Word	Noun	Adjective	Verb	Adverb
inflexible	No	Yes	No	No
stiff	Yes	Yes	No	Yes

inflexible (noun)	stiff (noun)
	the dead body of a human being
	an ordinary man

inflexible (adjective)	stiff (adjective)
resistant to being bent	having a strong physiological or chemical effect
incapable of change	rigidly formal
not making concessions	not moving or operating freely
incapable of adapting or changing to meet circumstances	very drunk
	marked by firm determination or resolution; not shakable
	strong, vigorous
	incapable of or resistant to bending

inflexible (adverb)	stiff (adverb)
	in a stiff manner
	to a great degree