peritoneum vs mesentery

peritoneum and mesentery both are nouns.

Word	Noun	Adjective	Verb	Adverb
peritoneum	Yes	No	No	No
mesentery	Yes	No	No	No

As nouns, mesentery is a hyponym of peritoneum; that is, mesentery is a word with a more specific, narrower meaning than peritoneum:

peritoneum: a transparent membrane that lines the abdominal cavity in mammals and covers most of the viscera
mesentery: a double layer of peritoneum that attaches to the back wall of the abdominal cavity and supports the small intestines

Other hyponyms of peritoneum include omentum.

peritoneum (noun)	mesentery (noun)
a transparent membrane that lines the abdominal cavity in mammals and covers most of the viscera	a double layer of peritoneum that attaches to the back wall of the abdominal cavity and supports the small intestines