peritonitis vs redness

peritonitis and redness both are nouns.

Word	Noun	Adjective	Verb	Adverb
peritonitis	Yes	No	No	No
redness	Yes	No	No	No

As nouns, redness is a hypernym of peritonitis; that is, redness is a word with a broader meaning than peritonitis:

peritonitis: inflammation of the peritoneum
redness: a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat

Other hypernyms of peritonitis include inflammation, rubor.

peritonitis (noun)	redness (noun)
inflammation of the peritoneum	red color or pigment; the chromatic color resembling the hue of blood
	a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat