| Term | Definition | Pronunciation |
| b.i.d. | bid twice a day | |
| Ba | barium | |
| BAC | blood alcohol concentration | |
| bacilli | A rod-shaped bacterium. | bah-sil´i |
| bacillus | A large genus of rod-shaped, gram-positive, spore-bearing bacteria. | |
| back | The rear surface from the shoulders to the hip. | |
| baclofen | A muscle relaxing drug. | |
| bacteremia | The presence of bacteria in the blood. Fever, chills, tachycardia, and tachypnea are common manifestations of bacteremia. | |
| bacteri- | bacteria | |
| bacteria | Single cell living things. One of the three domains of life. | bak-tēr´e-ah |
| bacterial endocarditis | Inflammation of the heart's lining or valves caused by bacteria in the bloodstream. | bak-tēr'ē-ăl en'dō-kahr-dī'tis |
| bactericide | A substance that kills bacteria. | |
| bacteriophage | A virus that attacks bacteria. | |
| bacteriuria | The presence of bacteria in the urine. Bacteriuria can be symptomatic or asymptomatic. | |
| BADL | basic activities of daily living | |
| balan/o | glans penis | |
| balanitis | Inflammation of the glans penis. | |
| balanoposthitis | Inflammation of the glans penis in uncircumcised males. | |
| ballism | Abnormal involuntary movements of the limbs. | |
| bandages | Material used for wrapping or binding any part of the body. Used to secure wound dressing or immobilize a limb. | |
| bar/o | pressure, weight | |
| barbiturate | A sedative that depresses respiratory rate, blood pressure, temperature and the central nervous system. | |
| bariatric surgery | Surgical procedures aimed at producing major weight reduction in patients with morbid obesity. | |
| bariatrics | Activities related to weight reduction in patients with obesity including diet, exercise, medication and surgery. | bar″e-at´riks |
| baroreceptor | One of the blood pressure sensitive nerve ending in heart's atria, aorta and the carotid sinuses. | |
| barotrauma | Injury caused by ambient pressure changes especially to the ear drums and lungs. | |
| barrier cream | Lotions and ointments used to protect the skin from allergens and irritants. | |
| bary- | heavy, hard, dull | |
| bas | basilar | |
| bas/o | base, bottom | |
| basal cell carcinoma | A malignant tumor. A common form of skin cancer. Metastasis is rare. | |
| basal ganglia | Large grey masses at the base of the cerebral hemisphere. | |
| basal metabolism | The minimum amount of energy needed to maintain vital body functions. | |
| basi- | base, foundation | |
| basilar membrane | A basement membrane in the cochlea that supports the hair cells of the organ of Corti. | |
| basophils | Granular leukocytes which stain blue-black with basic dyes. Active in inflammatory responses. | |
| bathy- | depth, deep | |
| battery | 1) The wrongful use of force on a person. 2) A electrical energy source formed by two or more electrolytic cells. | |
| bayes theorem | A probability theorem used in clinical decision analysis for estimating the probability of a particular diagnosis given the appearance of some symptoms or test result. | |
| BBB | bundle branch block | |
| BBT | basal body temperature | |
| BCLS | basic cardiac life support | |
| BE | below elbow | |
| bed rest | Confinement of an patient to bed for therapeutic reasons. | |
| behavior | The observable response of a man or animal to a situation. | |
| behaviorism | A psychologic theory, developed by John Broadus Watson, concerned with studying and measuring behaviors that are observable. | |
| Bell's Palsy | Temporary facial paralysis, 7th cranial nerve. Sudden onset. Usually one-side asymmetry. | |
| belly | The central fleshy part of a muscle. | |
| beneficence | The act of being kind, charitable, or beneficial. The ethical principle of beneficence requires that researchers should have the welfare of the research participant as a goal of any clinical trial. | |
| benign | Nonmalignant. A non-cancerous tumor. | |
| benzene | Toxic flammable liquid hydrocarbon byproduct of coal distillation. | |
| benzocaine | A local anesthetic applied topically. | |
| beriberi | A disorder caused by a deficiency of thiamine (vitamin B1) and characterized by heart failure and edema. | |
| beta blocker | Drugs that slow heart rate and reduce pumping force. Used to treat high blood pressure, angina, heart failure, migraines. | |
| betahistine | A histamine analog that serves as a vasodilator. Used to reduce the frequency of attacks of vertigo in Meniere's disease. | |
| betamethasone | A glucocorticoid administered by mouth, injection, inhalation or topically to treat disorders in which corticosteroids are indicated. | |
| bezoar | A mass of swallowed hair, fruit or vegetable fibers, or similar substances found in the alimentary canal. | |
| bi- | double, twice, two | |
| bi/o | life | |
| bias | Systematic deviation of results or inferences from the truth. | |
| bib. | drink | |
| bibli/o | books | |
| biceps | A muscle having two heads. Commonly used to refer to the muscles that extend from the shoulder joint to the elbow. | |
| biconcave | Concave on both sides, as in a lens design. | |
| biconvex | Convex on both sides, particularly in a lens design. | |
| bicuspid | A premolar tooth used for grinding food. | |
| bidet | A bathroom fixture, similar to a toilet bowel, used for cleaning the genital and rectal areas. | |
| bil/i | bile, gall | |
| bilat | bilateral | |
| bile | An emulsifying fluid produced in the liver, stored in the gall bladder and secreted into the duodenum. | |
| biliary | Pertaining to bile, the gall bladder or bile ducts. | |
| bilirubin | The orange-yellow pigment of bile. | |
| binaural | Relating to the use of both ears. | |
| binding sites | The parts of a macromolecule that directly participate in its specific combination with another molecule. | |
| binocular | Relating to the use of both eyes. | |
| bioassay | Laboratory determination of the potency of a drug or other substance by comparing its effects on living organisms with a standard preparation. | |
| biochemistry | The study of the composition, chemical structures, and chemical reactions of living things. | |
| bioethics | A branch of applied ethics that studies the value implications of practices and developments in life sciences, medicine, and health care. | |
| biofeedback | The therapy technique of providing immediate status of one's own body functions such as skin temperature, heartbeat, brain waves) as visual or auditory feedback in order to self-control related conditions. | |
| biohazard | Biological substances that pose a risk to the health of living organisms. | |
| biology | Studies concerned with the origin, structure, development, growth, function, genetics, and reproduction of animals, plants, and microorganisms. | |
| bionics | The science of mechanical and electrical systems that have characteristics of living systems. | |
| biophysics | The study of physical phenomena and physical processes as applied to living things. | |
| biopsy | Removal and pathologic examination of small pieces of tissue from the living body. | |
| biostatistics | The application of statistics to biological systems and organisms involving the retrieval or collection, analysis, reduction, and interpretation of qualitative and quantitative data. | |
| biotechnology | Techniques for applying biological processes to the production of materials for use in medicine, food production and industry. | |
| biotin | A water-soluble, enzyme co-factor present in minute amounts in every living cell. It is abundant in liver, kidney, pancreas, yeast, and milk. | |
| bipolar disorder | A major affective disorder marked by severe mood swings (manic or major depressive episodes) and a tendency to remission and recurrence. | |
| birthmark | A benign skin blemish present at birth. | |
| bisexuality | An individual who is sexually attracted to both sexes. | |
| BK | below the knee | |
| black eye | A contusion around the eye with discoloration and swelling. | |
| blackhead | A plug of fatty material in the outlet of the sebaceous gland in the skin. Comedo. | |
| blackwater fever | A complication of malaria characterized by acute renal failure and the passage of dark red to black urine. | |
| bladder | A hollow, expandable muscular sac that stores urine produced by the kidneys until excretion. | |
| blast- | bud, germ | |
| blastema | A mass of cells that is still growing and differentiating. | |
| blastocyst | The embryonic form that follows the morula in human development. | |
| blastula | An early non-mammalian embryo that follows the morula stage. A blastula resembles a hollow ball with the layer of cells surrounding a fluid-filled cavity. | |
| blenn- | mucus | |
| blephar/o | eyelid | |
| blepharitis | Inflammation of the eyelids. | |
| blepharoplasty | Cosmetic eyelid surgery. Also called eyelid lift. | blef·ə·rə‚plas·dē |
| blepharospasm | Spasmodic winking caused by the involuntary contraction of an eyelid muscle. | |
| blindness | The inability to see. | |
| blinking | Brief closing and reopening of the eyelids by involuntary or voluntary action. | |
| blister | Visible accumulations of watery fluid within or beneath the epidermis. | |
| blood | The body fluid that circulates in the vascular system. Whole blood in comprised of blood cells suspended in a liquid medium (plasma). | |
| blood banks | Centers for collecting, characterizing and storing human blood. | |
| blood cell | Any of the cells found in blood. This includes erythrocytes (red cells), leukocytes (white cells) and thrombocytes (platelets). | |
| blood clot | A semisolid mass formed by blood coagulation. Thrombus. | |
| blood coagulation | The process of the interaction of blood coagulation factors that results in an insoluble fibrin clot. | |
| blood count | The number of red or white blood cells in a specified volume of blood. | |
| blood glucose | The concentration of glucose in the blood. Also called blood sugar. Measured regularly in diabetes patients. | |
| blood group | Classification of blood based upon antigens on the surface of the red cell. Many blood grouping systems have been developed. The ABO system is one of the most important. | |
| blood plasma | The liquid part of the blood, free of formed elements and particles. | |
| blood pressure | Pressure of the blood on the arteries, veins and chambers of the heart. | |
| blood sugar | The concentration of glucose in the blood. Measured regularly in diabetes patients. | |
| blood transfusion | The administration of whole blood or a blood component into the blood stream. | |
| blood urea nitrogen | A measure of the concentration of urea in the blood | |
| blood vessels | Any of the tubular vessels conveying the blood (arteries, arterioles, capillaries, venules, and veins). | |
| BM | bowel movement | |
| BMD | bone mineral density | |
| BMI | body mass index | |
| BMR | basal metabolic rate | |
| BMT | bone marrow transplant | |
| body mass index | A formula for determining obesity based upon a person's weight and height. | |
| boil | A tender, inflamed area of skin that contains pus. | |
| bol | pill | |
| bolus | A soft mass of chewed food ready to be swallowed. | |
| bonding | The emotional attachment of mother-child or individuals to pets. | |
| bone | A dense, hard connective tissue that forms the framework of the skeleton. | |
| bone density | The amount of mineral per square centimeter of bone. Bone density is an important predictor for osteoporosis. | |
| bone marrow | The soft, spongy tissue filling the cavities of bones. Its primary function is to produce erythrocytes, leukocytes and platelets. | |
| borborygmus | Belching. | |
| borderline | Relating to health status where the patient has some signs and symptoms of an abnormality but insufficient for a definite diagnosis. | |
| botulism | A rare, but potentially fatal form of food poisoning caused by the bacterium Clostridium botulinum. | |
| bougie | A thin, cylindrical instrument, somewhat flexible, inserted into body canals in order to examine or dilate them. | |
| BP | blood pressure | |
| BPd | blood pressure diastolic | |
| BPH | benign prostatic hyperplasia | |
| bpm | beats per minute | |
| BPs | blood pressure systolic | |
| brachi/o | arm | |
| brachial | Relating to the arm. | |
| brachial artery | The continuation of the axillary artery; it branches into the radial and ulnar arteries. | |
| brachy- | short | |
| brachytherapy | Radiotherapy that uses small sources that are placed on or near tumor tissues. | |
| brady- | slow | |
| bradycardia | Cardiac arrhythmias that are characterized by abnormally slow heart rate, usually below 50 beats per minute in adults. | brăd′ĭ-kär′dē-ə |
| bradykinesia | Abnormally slow body movement. | |
| bradypnea | Slow breathing. | |
| braille | A system of printing for visually impaired people, consisting of raised dots that are read by touch. | |
| brain | A highly developed part of central nervous system that is contained within the cranium. It consists of cerebrum, cerebellum and other structures in the brain stem. | |
| breast | A mammary gland of women. | |
| breast implantation | Surgical insertion of a sac filled with silicone or other material to augment the female form cosmetically. | |
| breastfeeding | Feeding a baby milk from the breast. | |
| breath sounds | Sounds heard over the lungs and airways, usually with a stethoscope. | |
| breathing | The repeating cycle of inhaling and exhaling air into and out of the lungs. | |
| bregma | The juncture of the coronal and sagittal sutures on the top of the cranium. | |
| brom- | bromine, stench | |
| bronch/o | bronchial tube | |
| bronchi | The two large air tubes of the lungs branching from the trachea. Secondary bronchi, called bronchioles, branch from bronchi. | |
| bronchi/o | bronchial tube | |
| bronchiectasis | Persistent abnormal dilatation of the bronchi caused by chronic infection and inflammation. | brong'kē-ek'tă-sis |
| bronchitis | Inflammation of the large airways often caused by bacterial and viral infections and by cigarette smoke. | brŏng-kī′tĭs |
| bronchoconstriction | Narrowing of the lumen of the bronchi restricting airway into and out of the lungs. | |
| bronchodilator | Substance that expands the bronchi and bronchioles, increasing airflow to the lungs. | brŏng′kō-dī-lā′tər |
| bronchopulmonary | Pertaining to the bronchi and lungs. | |
| bronchorrhea | Abnormal discharge of mucus from the bronchi. | brong″ko-re´ah |
| bronchoscopes | Endoscopes for the visualization of the interior of the bronchi. | |
| bronchoscopy | Visual examination and possibly treatment of the bronchi, throat, larynx and trachea using a fiber optical device. | |
| bronchospasm | Excessive narrowing of the smooth muscles of the bronchi. Can be heard as a wheezing sound. | |
| bruise | A contusion. | |
| bruit | A murmur heard while auscultating the carotid artery. | |
| bruxism | A disorder characterized by grinding and clenching of the teeth. | |
| BSA | body surface area | |
| BSE | breast self-examination | |
| bubonic plague | Caused by the bite of a rat flea that has previously bitten an infected rat. | |
| bucc/o | cheek | |
| buccal | Relating to the mouth or inside of the cheek. | |
| buffer | A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer. | |
| -bulia | will | |
| bulimia | Eating an excess amount of food in a short period of time. It is caused by an abnormal craving for food. | |
| Bulimia Nervosa | An eating disorder characterized by binge eating followed by inappropriate purging (e.g. vomiting or using laxatives) to avoid weight gain. | bu-le´me-ah nĕr-vō'să |
| bulla | A fluid-filled blister with a diameter over 5 mm. | bul´ah |
| bullying | Aggressive behavior intended to cause harm or distress. The behavior may be physical or verbal. There is typically an imbalance of power, strength, or status between the target and the aggressor. | |
| BUN | blood urea nitrogen | |
| bundle branch block | A type of heart block where the electrical signals to the ventricles are interrupted at the Bundle of HIS, preventing the simultaneous depolarization of the two ventricles. | |
| bundle of his | Cells that conduct electrical impulses from the atrioventricular node to the ventricles. | |
| bunion | An area of thick tissue over the metatarsal phalangeal joint at the base of the great toe. | |
| bupropion | An antidepressant drug used as an aid to smoking cessation. | |
| burn | Tissue injury caused by heat, cold, chemicals, electricity, radiation and ultraviolet light. | |
| burs/o | bursa (fluid sac near joints) | |
| bursitis | Inflammation of a bursa, the fibrous sac that acts as a cushion between moving structures of bones, muscles, tendons or skin. | |
| butter | The fatty part of milk, separated when milk or cream is churned. A soft, solid, yellowish substance. | |
| buttocks | Either of two fleshy protuberances at the lower posterior section of the trunk or hip consisting of gluteal muscles and fat. | |
| butyr- | butter | |
| BW | body weight | |
| BWS | battered woman syndrome | |
| Bx | biopsy | |