If you're looking for words related to "gastric", you could consider these:
* Gastritis: inflammation of the stomach
* Gastroenteritis: inflammation of the stomach and intestines
* Gastroscopy: examination of the stomach using a gastroscope
* Gastric bypass: surgical procedure to help with weight loss
* Gastric ulcer: an open sore in the lining of the stomach
These words all use "gastric" as their root and add different suffixes to change their meaning.