Reference Library
Medical Terminology Glossary
Plain-language definitions for the words on your chart, prescription, and after-visit summary. Search below or jump to a letter.
A
- Acute
- Describes a condition that comes on suddenly and is often intense but short-lived — the opposite of chronic. An acute infection, for example, hits hard and fast.General Anatomy
- Anemia
- A condition where you don't have enough healthy red blood cells to carry adequate oxygen to your tissues, causing fatigue, weakness, and sometimes shortness of breath.Diagnoses
- Arrhythmia
- An irregular heartbeat — the heart may beat too fast, too slow, or with an erratic pattern. Some arrhythmias are harmless; others require treatment.Diagnoses
- Artery
- A blood vessel that carries oxygen-rich blood away from the heart to the rest of the body. Arteries have thick, elastic walls to handle the pressure of each heartbeat.General Anatomy
B
- Benign
- Not cancerous. A benign tumor or growth does not invade nearby tissue or spread (metastasize) to other parts of the body.Diagnoses
- Biopsy
- A procedure where a small sample of tissue is removed from the body and examined under a microscope to check for cancer, infection, or other abnormalities.Procedures
- BMI (Body Mass Index)
- A number calculated from your height and weight used to broadly estimate whether you fall in an underweight, healthy, overweight, or obese range. It's a screening tool, not a diagnosis.General Anatomy
- BMP (Basic Metabolic Panel)
- A blood test checking 8 key substances — blood sugar, calcium, and 6 electrolytes/kidney markers — to screen for diabetes, kidney disease, and electrolyte imbalances.Lab/Test Terms
- Bradycardia
- A resting heart rate slower than 60 beats per minute. In athletes it can be normal; in others it may cause dizziness, fatigue, or fainting.Diagnoses
C
- CBC (Complete Blood Count)
- One of the most common blood tests ordered. It measures red blood cells, white blood cells, platelets, hemoglobin, and hematocrit to screen for anemia, infection, and more.Lab/Test Terms
- Chronic
- A condition that lasts three months or longer and often requires ongoing management rather than a one-time cure — for example, diabetes or asthma.General Anatomy
- Colonoscopy
- A procedure using a flexible camera inserted through the rectum to examine the entire colon. It's the gold standard for colorectal cancer screening and can remove polyps on the spot.Procedures
- Contraindication
- A reason why a specific drug, treatment, or procedure should NOT be used — for example, certain blood thinners are contraindicated in people with active bleeding.Medications
- Creatinine
- A waste product produced by muscles and filtered by the kidneys. Elevated blood creatinine levels can signal that the kidneys are not working as well as they should.Lab/Test Terms
- CT Scan (Computed Tomography)
- An imaging test that combines X-rays taken from many angles with computer processing to create detailed cross-sectional images of bones, blood vessels, and soft tissues.Procedures
D
- Diagnosis
- The identification of a disease or condition based on a patient's symptoms, medical history, physical exam, and test results.Diagnoses
- Differential Diagnosis
- The process doctors use to distinguish one disease from others with similar symptoms. Think of it as a ranked list of possible explanations for your condition.Diagnoses
E
- ECG / EKG (Electrocardiogram)
- A quick, painless test that records the heart's electrical activity using sticky patches on your skin. It's used to detect arrhythmias, heart attacks, and structural heart problems.Lab/Test Terms
- Echocardiogram
- An ultrasound of the heart that produces real-time images showing the heart's size, shape, pumping strength, and valve function — no radiation involved.Procedures
- Edema
- Swelling caused by excess fluid trapped in your body's tissues, commonly noticed in the legs, ankles, or feet. It can be a sign of heart, kidney, or liver problems.General Anatomy
- eGFR (Estimated Glomerular Filtration Rate)
- A calculated estimate of how well your kidneys are filtering waste from your blood. An eGFR below 60 for three months or more suggests chronic kidney disease.Lab/Test Terms
- Endoscopy
- A procedure using a thin, flexible tube with a camera to look inside the digestive tract — typically the esophagus, stomach, or colon — to diagnose or treat conditions.Procedures
F
- Ferritin
- A protein that stores iron in your body. Blood ferritin levels are the best single indicator of your body's total iron stores — low levels suggest iron deficiency.Lab/Test Terms
G
- Generic Drug
- A medication with the same active ingredient, dosage form, and effect as a brand-name drug, typically sold at a significantly lower cost after the brand's patent expires.Medications
H
- HbA1c (Hemoglobin A1c)
- A blood test that reflects your average blood sugar levels over the past 2–3 months. It's used to diagnose diabetes (≥6.5%) and prediabetes (5.7–6.4%) and to monitor how well diabetes is controlled.Lab/Test Terms
- Hemoglobin
- The protein inside red blood cells that carries oxygen from your lungs to your body's tissues and returns carbon dioxide back to the lungs to be exhaled.Lab/Test Terms
- Hypertension
- High blood pressure — when the force of blood against artery walls is consistently too high (130/80 mmHg or above). It's a major risk factor for heart disease and stroke.Diagnoses
- Hypotension
- Abnormally low blood pressure, typically below 90/60 mmHg. It can cause dizziness, lightheadedness, and fainting, especially when standing up quickly.Diagnoses
I
- Inflammation
- The body's natural response to injury or infection, marked by redness, warmth, swelling, and pain. Short-term inflammation is protective; long-term (chronic) inflammation can damage tissues.General Anatomy
L
- Lipid Panel
- A blood test measuring total cholesterol, LDL ('bad') cholesterol, HDL ('good') cholesterol, and triglycerides — used to assess your risk of heart disease and stroke.Lab/Test Terms
- Lymph Node
- Small, bean-shaped glands throughout the body that filter lymph fluid and help fight infection as part of the immune system. Swollen lymph nodes are often a sign your body is fighting illness.General Anatomy
M
- Malignant
- Cancerous. A malignant tumor can invade surrounding tissue and spread to other parts of the body through the blood or lymphatic system.Diagnoses
- MRI (Magnetic Resonance Imaging)
- An imaging test that uses strong magnets and radio waves (no radiation) to produce highly detailed images of soft tissue, organs, and the brain — especially useful for joints and the spine.Procedures
O
- Off-Label
- When a medication is prescribed for a purpose, age group, or dose not officially approved by the FDA — a legal and common practice when evidence supports the use.Medications
P
- Palliative
- Care or treatment focused on relieving symptoms and improving quality of life rather than curing the underlying disease. Palliative care can be given alongside curative treatment.Medications
- Pathology
- The medical specialty that studies disease, or the report from a lab describing the analysis of tissue or cells removed during a biopsy or surgery.Procedures
- Platelet
- Tiny blood cells that stick together to form clots and stop bleeding. Low platelets (thrombocytopenia) can cause excessive bleeding; high platelets may indicate inflammation.Lab/Test Terms
- Prognosis
- A forecast of how a disease is likely to progress — including the likelihood of recovery, remission, or complications. Prognosis is based on statistics, not a certainty.Diagnoses
- Prophylactic
- Something taken to prevent a disease or condition before it occurs. For example, a daily low-dose aspirin may be prophylactic against heart attacks in certain patients.Medications
R
- Red Blood Cell (RBC)
- Cells produced in the bone marrow that carry oxygen via hemoglobin throughout the body. A low RBC count is a key sign of anemia.Lab/Test Terms
T
- Tachycardia
- A resting heart rate faster than 100 beats per minute. It can be caused by anxiety, dehydration, infection, heart problems, or other conditions.Diagnoses
- TSH (Thyroid Stimulating Hormone)
- A hormone produced by the pituitary gland that tells the thyroid to produce thyroid hormones. A high TSH suggests an underactive thyroid (hypothyroidism); a low TSH suggests an overactive thyroid.Lab/Test Terms
U
- Urinalysis
- A test that analyzes a urine sample for protein, glucose, blood, bacteria, and other markers to screen for urinary tract infections, kidney disease, and diabetes.Lab/Test Terms
V
- Vein
- A blood vessel that carries blood back toward the heart, usually oxygen-depleted blood from the body's tissues. Veins have thinner walls than arteries and contain valves to prevent backflow.General Anatomy
W
- White Blood Cell (WBC)
- Immune cells that fight infections, viruses, and abnormal cells. A high WBC count often indicates active infection or inflammation; a very low count can leave you vulnerable to illness.Lab/Test Terms