Last reviewed: February 2026

📖 GI Terminology Glossary

Understanding medical terms related to digestive health

🔤 A

Abdomen
The area of the body between the chest and pelvis containing digestive organs; commonly called the belly or stomach area.
Achalasia
A condition where the esophagus cannot move food properly into the stomach due to nerve damage; causes difficulty swallowing.
Acid reflux
When stomach acid flows back into the esophagus, causing heartburn and discomfort. Also called gastroesophageal reflux.
Acute
Sudden onset, severe, and usually short-term (opposite of chronic).
Adhesions
Bands of scar tissue that form between abdominal organs, often after surgery; can cause pain or obstruction.
Albumin
A protein made by the liver; low levels may indicate liver disease or malnutrition.
Alkaline phosphatase (ALP)
An enzyme measured in blood tests; elevated levels may indicate liver or bile duct problems.
Anastomosis
Surgical connection between two body parts, like joining two sections of intestine after removing a diseased portion.
Anemia
Low red blood cell count; in GI context, often caused by bleeding or poor absorption of iron/B12.
Anorectal
Relating to the anus and rectum.
Antacid
Medication that neutralizes stomach acid to relieve heartburn and indigestion.
Antiemetic
Medication that prevents or treats nausea and vomiting.
Anus
The opening at the end of the digestive tract through which stool leaves the body.
Appendicitis
Inflammation of the appendix, causing severe right lower abdominal pain; usually requires surgery.
Ascites
Abnormal buildup of fluid in the abdomen, often due to liver disease.
Autoimmune
Condition where the immune system attacks the body's own tissues (e.g., autoimmune hepatitis, celiac disease).

🔤 B

Barium
A contrast material swallowed or given as enema to make digestive organs visible on X-rays.
Barrett's esophagus
A condition where cells lining the lower esophagus change due to chronic acid reflux; increases cancer risk.
Bile
Green-yellow fluid made by the liver, stored in gallbladder, helps digest fats.
Bile duct
Tubes that carry bile from the liver and gallbladder to the small intestine.
Biliary
Relating to bile, bile ducts, or gallbladder.
Bilirubin
Yellow pigment from red blood cell breakdown; high levels cause jaundice.
Biopsy
Removing a small tissue sample for examination under microscope to diagnose disease.
Bloating
Feeling of fullness, tightness, or swelling in the abdomen, often due to gas.
Borborygmi
Medical term for stomach/intestinal rumbling or gurgling sounds.
Bowel
Another term for intestine (small bowel = small intestine, large bowel = colon).
Bristol Stool Chart
A medical scale classifying stool into 7 types based on shape and consistency; helps describe bowel movements to doctors.

🔤 C

Celiac disease
Autoimmune condition where eating gluten damages the small intestine; requires lifelong gluten-free diet.
Cholangitis
Infection of the bile ducts, often due to blockage; serious condition requiring urgent treatment.
Cholecystectomy
Surgical removal of the gallbladder.
Cholecystitis
Inflammation of the gallbladder, usually due to gallstones.
Cholelithiasis
Medical term for gallstones.
Chronic
Long-lasting or recurring condition (opposite of acute).
Cirrhosis
Severe scarring of the liver due to long-term damage; affects liver function.
Colectomy
Surgical removal of part or all of the colon.
Colic
Cramping pain that comes and goes, often in waves.
Colitis
Inflammation of the colon; can be due to infection, IBD, or other causes.
Colon
The large intestine; absorbs water and forms stool.
Colonoscopy
Examination of the colon using a flexible camera tube inserted through the anus.
Colorectal
Relating to the colon and rectum.
Constipation
Infrequent bowel movements or difficulty passing stool.
Contrast
Substances used in imaging tests to make organs more visible (barium, iodine-based).
Crohn's disease
Type of inflammatory bowel disease that can affect any part of the digestive tract; causes inflammation, ulcers, and various symptoms.

🔤 D

Defecation
Medical term for passing stool; bowel movement.
Dehydration
Loss of body fluids beyond normal; can result from diarrhea, vomiting, or inadequate intake.
Diarrhea
Loose, watery stools occurring more frequently than normal.
Digestion
Process of breaking down food into nutrients the body can absorb and use.
Diverticulitis
Infection or inflammation of diverticula (pouches in the colon wall).
Diverticulosis
Presence of diverticula (small pouches) in the colon wall; common with aging, usually asymptomatic.
Duodenum
First part of the small intestine, connecting to the stomach.
Dyspepsia
Medical term for indigestion; discomfort in upper abdomen.
Dysphagia
Difficulty swallowing food or liquids.

🔤 E

Edema
Swelling due to fluid accumulation in tissues.
Emesis
Medical term for vomiting.
Encephalopathy (hepatic)
Brain dysfunction due to liver failure; causes confusion, personality changes.
Endoscope
Flexible tube with camera used to examine inside the digestive tract.
Endoscopy
Procedure using an endoscope to examine or treat the digestive system.
Enema
Liquid inserted into the rectum to clean the bowel or administer medication.
Enteral
Through the digestive tract; enteral nutrition = feeding through a tube into stomach/intestine.
Enteritis
Inflammation of the small intestine.
Enzyme
Protein that speeds up chemical reactions; digestive enzymes break down food.
ERCP
Endoscopic Retrograde Cholangiopancreatography - procedure to examine and treat bile duct and pancreatic problems.
Erosion
Wearing away of tissue surface; gastric erosion = damage to stomach lining.
Esophagitis
Inflammation of the esophagus, often due to acid reflux.
Esophagus
The tube connecting the throat to the stomach; food pipe.
EUS
Endoscopic Ultrasound - combining endoscopy with ultrasound for detailed imaging.

🔤 F

Fatty liver
Accumulation of fat in liver cells; can be alcohol-related or non-alcoholic (NAFLD).
Fecal
Relating to feces (stool).
Fiber
Plant material that cannot be fully digested; important for healthy bowel function.
Fibrosis
Scarring of tissue; liver fibrosis = early scarring before cirrhosis.
FibroScan
Non-invasive test measuring liver stiffness to assess fibrosis/cirrhosis.
Fissure (anal)
Small tear in the lining of the anus, causing pain and bleeding with bowel movements.
Fistula
Abnormal tunnel connecting two body parts that shouldn't be connected (e.g., between intestine and skin).
Flare
Period when a chronic condition becomes more active; symptom worsening.
Flatulence
Passing gas from the digestive system through the anus.
FODMAP
Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols - carbohydrates that can trigger IBS symptoms.
Fundoplication
Surgery to treat severe reflux by wrapping the stomach around the lower esophagus.

🔤 G

Gallbladder
Small organ under the liver that stores bile.
Gallstones
Hard deposits that form in the gallbladder; can cause pain if they block bile ducts.
Gastrectomy
Surgical removal of part or all of the stomach.
Gastric
Relating to the stomach.
Gastritis
Inflammation of the stomach lining.
Gastroenteritis
Inflammation of stomach and intestines, usually due to infection; "stomach flu."
Gastroenterologist
Doctor specializing in digestive system diseases.
Gastroesophageal reflux disease (GERD)
Chronic acid reflux causing symptoms like heartburn; stomach acid regularly flows back into esophagus.
Gastrointestinal (GI)
Relating to the stomach and intestines; digestive system.
Gastroparesis
Delayed stomach emptying due to nerve damage; causes nausea, vomiting, bloating.
Gastroscopy
Endoscopy of the stomach; upper GI endoscopy.
GGT (Gamma-glutamyl transferase)
Liver enzyme measured in blood tests; elevated in liver disease, especially alcohol-related.
Gluten
Protein found in wheat, barley, rye; triggers damage in celiac disease.

🔤 H

H. pylori (Helicobacter pylori)
Bacteria that can infect the stomach, causing ulcers and gastritis; treatable with antibiotics.
Heartburn
Burning sensation in chest due to acid reflux; not actually related to the heart.
Hematochezia
Passage of fresh red blood from the rectum.
Hematemesis
Vomiting blood.
Hemorrhoids (piles)
Swollen blood vessels in the rectum or anus; can cause bleeding, pain, itching.
Hepatic
Relating to the liver.
Hepatitis
Inflammation of the liver; can be due to viruses (A, B, C, etc.), alcohol, medications, or autoimmune disease.
Hepatologist
Doctor specializing in liver diseases.
Hepatomegaly
Enlarged liver.
Hernia
Protrusion of an organ through a weak spot in surrounding tissue; abdominal hernias involve intestine.
Hiatal hernia
When part of the stomach pushes up through the diaphragm into the chest; can worsen reflux.

🔤 I-J-K

IBD (Inflammatory Bowel Disease)
Chronic inflammation of the digestive tract; includes Crohn's disease and ulcerative colitis.
IBS (Irritable Bowel Syndrome)
Common functional disorder causing abdominal pain, bloating, and altered bowel habits without structural damage.
Icterus
Medical term for jaundice; yellowing of skin and eyes due to bilirubin buildup.
Ileostomy
Surgical opening connecting the small intestine (ileum) to the abdominal wall for waste elimination.
Ileum
Last part of the small intestine, connecting to the colon.
Ileus
Temporary stopping of intestinal movement, often after surgery; different from obstruction.
Incontinence (fecal)
Inability to control bowel movements.
Intussusception
When one part of intestine slides into another, causing obstruction; more common in children.
Jaundice
Yellow discoloration of skin and eyes due to high bilirubin; indicates liver, gallbladder, or blood cell problems.
Jejunum
Middle section of the small intestine, between duodenum and ileum.

🔤 L-M

Lactose intolerance
Inability to digest lactose (milk sugar) due to lacking the enzyme lactase; causes bloating, gas, diarrhea after dairy.
Laparoscopy
Minimally invasive surgery using small incisions and a camera; "keyhole surgery."
Laxative
Medication that promotes bowel movements; used for constipation.
Lesion
Abnormal area of tissue; can be ulcer, growth, or other abnormality.
LFT (Liver Function Tests)
Blood tests measuring liver enzymes and function (ALT, AST, ALP, bilirubin, albumin, etc.).
Liver
Large organ in upper right abdomen; processes nutrients, makes bile, detoxifies blood, produces proteins.
Lumen
The inside space of a hollow organ like the intestine.
Malabsorption
Inability to properly absorb nutrients from food; causes deficiencies and diarrhea.
Melena
Black, tarry stool indicating bleeding from upper digestive tract.
Mesentery
Tissue that attaches intestines to the abdominal wall; contains blood vessels.
Microbiome
Community of microorganisms (bacteria, etc.) living in the digestive system.
Motility
Movement of the digestive tract; peristalsis pushing food through.
Mucosa
Inner lining of the digestive tract.
Mucus
Slippery substance protecting and lubricating the digestive tract lining.

🔤 N-O

NAFLD (Non-Alcoholic Fatty Liver Disease)
Fat accumulation in liver not caused by alcohol; common with obesity and diabetes.
NASH (Non-Alcoholic Steatohepatitis)
More severe form of NAFLD with inflammation; can progress to cirrhosis.
Nausea
Feeling of needing to vomit.
Necrosis
Death of tissue.
NGT (Nasogastric tube)
Tube passed through nose into stomach for feeding or draining stomach contents.
NPO
"Nothing by mouth" (nil per os) - medical instruction to not eat or drink, usually before procedures.
Obstruction (bowel)
Blockage preventing contents from moving through the intestine; medical emergency.
Occult blood
Blood in stool not visible to naked eye; detected by special tests.
Odynophagia
Pain when swallowing (different from difficulty swallowing).
OGD (Oesophagogastroduodenoscopy)
Upper GI endoscopy examining esophagus, stomach, and duodenum.
ORS (Oral Rehydration Solution)
Mixture of water, salts, and sugar to treat dehydration from diarrhea/vomiting.

🔤 P

Pancreas
Organ behind the stomach that produces digestive enzymes and hormones (insulin).
Pancreatitis
Inflammation of the pancreas; causes severe abdominal pain; can be acute or chronic.
Parenteral
Not through the digestive tract; parenteral nutrition = IV feeding.
Peptic ulcer
Sore in the lining of stomach (gastric ulcer) or duodenum (duodenal ulcer).
Perforation
Hole through the wall of an organ; bowel perforation is a surgical emergency.
Peristalsis
Wave-like muscle contractions that move food through the digestive tract.
Peritoneum
Membrane lining the abdominal cavity and covering organs.
Peritonitis
Infection/inflammation of the peritoneum; serious condition requiring urgent treatment.
Polyp
Growth projecting from mucous membrane; colon polyps can become cancerous.
Portal hypertension
High blood pressure in the portal vein (carries blood to liver); complication of cirrhosis.
PPI (Proton Pump Inhibitor)
Medications that strongly reduce stomach acid production (omeprazole, pantoprazole, etc.).
Probiotic
Live beneficial bacteria taken to support gut health.
Proctitis
Inflammation of the rectum.
Prognosis
Expected outcome or course of a disease.
Prolapse (rectal)
When the rectum protrudes through the anus.

🔤 R-S

Rectum
Last part of the large intestine, ending at the anus; stores stool before elimination.
Reflux
Backward flow; usually refers to stomach contents flowing back into esophagus.
Regurgitation
Return of food from stomach to mouth without the effort of vomiting.
Remission
Period when disease symptoms are reduced or absent.
Resection
Surgical removal of part of an organ.
Sigmoidoscopy
Examination of the sigmoid colon (last part before rectum) using a scope.
Small intestine
Long tube between stomach and colon where most nutrient absorption occurs; includes duodenum, jejunum, ileum.
Sphincter
Ring of muscle that controls passage between parts of digestive tract (e.g., lower esophageal sphincter).
Spleen
Organ in left upper abdomen; part of immune system, can enlarge with liver disease.
Steatorrhea
Fatty, foul-smelling stool indicating fat malabsorption.
Stenosis
Abnormal narrowing of a passage.
Stoma
Surgically created opening connecting internal organ to body surface (for ostomy bags).
Stool
Feces; waste matter discharged from the bowels.
Stricture
Abnormal narrowing of a passage due to scarring or inflammation.

🔤 T-U-V-W

Tenesmus
Feeling of needing to pass stool even when bowels are empty; constant urge.
Transit time
Time for food to travel through the digestive system.
Transaminases
Liver enzymes (ALT, AST) measured in blood tests; elevated in liver damage.
Ulcer
Open sore on skin or mucous membrane; digestive ulcers occur in stomach/duodenum.
Ulcerative colitis
Type of IBD causing inflammation and ulcers in the colon and rectum.
Upper GI
Upper gastrointestinal tract; esophagus, stomach, and duodenum.
Varices
Enlarged, swollen veins; esophageal varices can bleed dangerously in liver disease.
Villus (plural: villi)
Tiny finger-like projections in small intestine that absorb nutrients; damaged in celiac disease.
Viscera
Internal organs, especially of the abdomen.
Volvulus
Twisting of intestine causing obstruction; surgical emergency.

📚 Key Takeaways