Stomach
Gastrointestine
noun, な adjective, の adjective
Intestines and stomach make up the stomach in your body.
いちょう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
胃腸がそんなに丈夫な方ではありません。
My stomach isn’t very strong.