Medical terminology:

A- / An-

Without, missing, or completely lacking (e.g., Anoxia = no oxygen).

Brady-

Abnormally slow (e.g., Bradycardia = slow heart rate).

Tachy-

Abnormally fast (e.g., Tachycardia = fast heart rate).

Hyper-

High, excessive, or overactive (e.g., Hyperglycemia = high blood sugar).

Hypo-

Low, under, or deficient (e.g., Hypoxia = low oxygen in tissues).

Isch-

Restriction, blocking, or holding back (e.g., Ischemia = blocked blood flow).

Poly-

Many, excessive, or frequent (e.g., Polyuria = excessive urination).

Olig- / Oligo-

Scant, few, or exceptionally low (e.g., Oliguria = low urine output).

Dys-

Bad, painful, abnormal, or difficult (e.g., Dyspnea = difficult breathing).

Idio-

Self, individual, or distinct (e.g., Idiopathic = unknown primary cause).

Iatro-

Caused by a physician, medicine, or treatment (e.g., Iatrogenic infection).

Hem- / Hemo- / Hemat-

Relating to blood (e.g., Hematuria = blood in the urine).

Leuko-

White (e.g., Leukocyte = white blood cell).

Erythro-

Red (e.g., Erythrocyte = red blood cell).

Neo-

New (e.g., Neoplasm = new cellular growth/tumor).

-itis

Inflammation of a tissue or organ (e.g., Gastritis = inflamed stomach).

-oma

Tumor, mass, or fluid collection (e.g., Melanoma = skin cancer tumor).

-lysis

Destruction, breaking down, or bursting open (e.g., Hemolysis = destruction of red blood cells).

-megaly

Enlargement of an organ (e.g., Cardiomegaly = enlarged heart).

-pathy

Disease, disorder, or morbid condition (e.g., Nephropathy = kidney disease).

-penia

Deficiency, lack of, or abnormal reduction (e.g., Leukopenia = low white blood cell count).

-pnea

Relating to breathing or respiration (e.g., Tachypnea = fast breathing).

-uria

Present in the urine (e.g., Proteinuria = protein in the urine).

-emia

Present in the blood (e.g., Toxemia = toxins in the blood).

-genic

Originating from, produced by, or caused by (e.g., Cardiogenic = caused by the heart).

-algia

Pain in a specific area (e.g., Arthralgia = joint pain).

-stasis

Stopping, slowing down, or standing still (e.g., Hemostasis = stopping blood flow).

-emesis

The act of vomiting (e.g., Hematemesis = vomiting blood).

-ectasis

Dilation, stretching, or expansion of a tubular structure (e.g., Atelectasis = collapsed lung/incomplete expansion).

Cardi/o

Heart.

Myo-

Muscle.

Angi/o or Vas/o

Blood vessel.

Arteri/o

Artery.

Thromb/o

Blood clot.

Gastr/o

Stomach.

Enter/o

Intestines.

Hepat/o

Liver.

Chlo/e

Bile or gall.

Cyst/o

Bladder or a fluid-filled sac.

Nephr/o or Ren/o

Kidney.

Pneum/o or Pulmon/o

Lungs.

Encephal/o

Brain.

Mening/o

Meninges (protective membranes surrounding the brain and spinal cord).

Arthr/o

Joint.

Oste/o

Bone.

Glyc/o

Glucose or sugar.

Lith/o

Stone or calculus.

Sign

An objective, measurable finding observed by a clinician (e.g., fever, rash, high blood pressure).

Symptom

A subjective experience felt and reported exclusively by the patient (e.g., pain, nausea, dizziness, fatigue).

Etiology

The precise root cause or origin of a medical condition or disease.

Pathogenesis

The step-by-step cellular and physiological development or progression of a disease.

Necrosis

Accidental, unprogrammed cell death caused by external injury or disease, leading to tissue inflammation.

Apoptosis

Highly programmed, orderly "cell suicide" that removes unwanted or damaged cells without causing surrounding inflammation.

Perfusion

The physiological process of delivering oxygenated blood to the body's capillary beds and vital organs.

Vasodilation

The widening and relaxation of blood vessels, which causes system-wide blood pressure to drop.

Vasoconstriction

The narrowing and tightening of blood vessels, which raises system-wide blood pressure.

Anaplasia

A total loss of cellular differentiation and structure, which is a key hallmark of highly malignant, aggressive cancers.

Ascites

An abnormal accumulation of protein-rich fluid in the abdominal cavity, typically caused by severe liver failure (Cirrhosis).

Jaundice

A yellow tinting of the skin and eyes caused by an abnormal buildup of bilirubin in the blood due to liver or gallbladder failure.

Hemoptysis

The coughing up or spitting of blood or blood-stained mucus from the respiratory tract.

Paresthesia

An abnormal sensation of burning, prickling, or a "pins-and-needles" feeling on the skin.

Ptosis

Abnormal drooping of the upper eyelid, usually caused by nerve damage or muscle weakness (classic sign of Myasthenia Gravis).

Diplopia

Visually seeing two images of a single object simultaneously; commonly known as double vision.