gastrointestinal

(Abbr. GI) Relating to the stomach and the intestines.

Pertaining to the stomach and intestine.

• g. foreign body — see intestinal obstruction.
• g. hormones — hormones secreted by the gastrointestinal epithelium that affect the function of the tract itself and of its allied organs, e.g. gastrin, glucagon, enteroglucagon, somatostatin, secretin, cholecystokinin-pancreozymin, motilin, gastric inhibitory polypeptide, vasoactive intestinal polypeptide.
• g. series — a radiological examination of the upper gastrointestinal tract using barium as the contrast medium for a series of x-ray films. Called also a barium meal. See barium study.
• g. tract — the stomach and intestines in continuity. See also digestive system.

The adjective has one meaning:

Meaning #1: of or relating to the stomach and intestines
  Synonym: gi
  Pertains to noun: gastrointestinal tract (meaning #1)