dead body vs stiff

dead body and stiff both are nouns.

Word	Noun	Adjective	Verb	Adverb
dead body	Yes	No	No	No
stiff	Yes	Yes	No	Yes

As nouns, stiff is a hyponym of dead body; that is, stiff is a word with a more specific, narrower meaning than dead body:

Other hyponyms of dead body include kill, carcase, carcass, carrion, roadkill, cadaver, clay, corpse, remains, mummy.

dead body (noun)	stiff (noun)
a natural object consisting of a dead animal or person	the dead body of a human being
	an ordinary man

dead body (adjective)	stiff (adjective)
	having a strong physiological or chemical effect
	rigidly formal
	not moving or operating freely
	very drunk
	marked by firm determination or resolution; not shakable
	strong, vigorous
	incapable of or resistant to bending

dead body (adverb)	stiff (adverb)
	in a stiff manner
	to a great degree