gastrointestinal tract vs GI tract

gastrointestinal tract and GI tract both are nouns.

Word	Noun	Adjective	Verb	Adverb
gastrointestinal tract	Yes	No	No	No
GI tract	Yes	No	No	No

As nouns, gastrointestinal tract and GI tract are synonyms defined as:

gastrointestinal tract and GI tract: tubular passage of mucous membrane and muscle extending about 8.3 meters from mouth to anus; functions in digestion and elimination

Other synonyms of gastrointestinal tract include alimentary canal, alimentary tract, digestive tract, digestive tube.

gastrointestinal tract (noun)	GI tract (noun)
tubular passage of mucous membrane and muscle extending about 8.3 meters from mouth to anus; functions in digestion and elimination	tubular passage of mucous membrane and muscle extending about 8.3 meters from mouth to anus; functions in digestion and elimination