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DDS - Doctor of Dental Surgery; a dentist.
Debridement - the surgical removal of foreign material and/or dead, damaged, or infected tissue from a wound or burn.
Decibel - unit of measuring the intensity or loudness of sound.
Deciduous teeth - also known as "baby" or primary teeth.
Deep vein thrombosis (DVT) - blockage of the deep veins; particularly common in the leg.
Defecation - passage of bowel contents through the rectum and anus.
Defecography - an X-ray of the anorectal area that evaluates completeness of stool elimination, identifies anorectal abnormalities, and evaluates rectal muscle contractions and relaxation.
Defibrillator - an electronic device used to establish a normal heartbeat.
Dehydration - loss of fluids from the body, often caused by diarrhea and/or vomiting.
Delayed gastric emptying (also called gastroparesis) - a condition in which the stomach's ability to empty its contents into the small intestine is decreased, but no obstruction exists. This causes slow digestion and emptying, vomiting, nausea, or bloating.
Delusions - a perception that is thought to be true by the person experiencing it, although the perception is wrong. There are many types of delusions (i.e., delusions of grandeur).
Dementia - commonly defined as a decline in intellectual functioning that is severe enough to interfere with the ability to perform routine activities. Dementia is not a disease itself but a group of symptoms that characterize certain diseases and conditions, such as Alzheimer's disease.
Dendrite - a threadlike extension from a nerve cell that serves as an antenna to receive messages from the axons of other nerve cells.
Dengue fever - a viral disease transmitted by Aedes mosquitoes that occurs mainly in tropical and subtropical areas of the world.
Dental amalgams (also called silver fillings) - dental fillings that are comprised of a mixture of mercury (45 to 50 percent), and an alloy of silver, tin, and copper (50 to 55 percent).
Dental fluorosis - a condition that results from drinking overly fluoridated water that often causes the teeth to become discolored and the enamel of the teeth to look spotted, pitted, or stained.
Dental implants - small dental appliances that are inserted into the upper and lower jaws to help restore missing teeth.
Dental pulp - the soft tissue inside the tooth that contains nerves, blood vessels, and connective tissue.
Dental sealant - a thin, plastic film that is painted on the chewing surfaces of the back teeth - the molars and premolars - to prevent tooth decay.
Dependent personality disorder - a mental disorder in which a person relies heavily on others for validation and fulfillment of basic needs. Often unable to properly care for themselves, people with dependent personality disorder lack self-confidence and security, and are deficient in making decisions.
Depression - a depressive disorder characterized by extreme feelings of sadness, lack of self-worth, and dejection.
Depth perception - the ability to distinguish objects in a visual field.
Dermabrasion - a procedure used to minimize small scars, minor skin surface irregularities, surgical scars, and acne scars. As the name implies, dermabrasion involves removing the top layers of skin with an electrical machine that "abrades" the skin. As the skin heals from the procedure, the surface appears smoother and fresher.
Dermaplaning - a plastic surgery technique used to treat deep acne scars with a hand-held instrument called a dermatome.
Dermatitis - an inflammation of the skin characterized by redness and itching.
Dermatofibroma - small, red or brown bumps in the skin.
Dermatome - an instrument that resembles an electric razor and has an oscillating blade that moves back and forth to evenly "skim" off the surface layers of skin that surround craters or other facial defects.
Dermatopathology - the study of the skin in diagnosing skin diseases.
Dermis - the middle layer of skin, which is made up of blood vessels, lymph vessels, hair follicles, sweat glands, collagen bundles, and fibroblasts.
Dermoid cyst - a benign tumor made up of hairs, sweat glands, and sebaceous glands.
Descending colon - the middle part of the colon located on the left side of the abdomen.
DEXA (dual energy X-ray absorptiometry) - imaging technique that uses a very low dose of radiation to measure bone density for the diagnosis of osteoporosis.
Diabetes mellitus - disorder that occurs when the body is not able to use sugar for growth and energy for daily activities. There are two main types of diabetes mellitus: insulin-dependent (Type 1) and noninsulin-dependent (Type 2).
Diagnosis - identifying a disease by its signs, symptoms, and laboratory findings.
Diagnostic mammogram - an X-ray of the breast used to diagnose unusual breast changes, such as a lump, pain, nipple thickening or discharge, or a change in breast size or shape. A diagnostic mammogram is also used to evaluate abnormalities detected on a screening mammogram.
Diagnostic radiology - the use of various radiological techniques, mostly noninvasive, to diagnose an array of medical conditions. Diagnostic radiology includes the use of X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and ultrasound.
Dialysis - a medical procedure used to remove wastes and additional fluid from the blood after the kidneys have stopped functioning.
Diaper rash - an irritation of the skin in the diaper area.
Diaphragm - primary muscle used for respiration, located just below the lung bases.
Diarrhea - frequent, loose, and watery bowel movements.
Diastolic blood pressure - the lowest blood pressure measure in the arteries, which occurs between heartbeats.
Diathermy machine - a piece of equipment used to heat body tissues for various purposes.
Diffuse axonal injury (DAI) - the shearing (tearing) of the brain's long connecting nerve fibers (axons) that can occur with severe brain injury.
Digestants - medications that aid or stimulate digestion.
Digestion - process the body uses to break down food into simple substances for energy, growth, and cell repair.
Digestive system - the group of organs that breaks down foods into chemical components that the body can absorb and use for energy, and for building and repairing cells and tissues.
Digital rectal examination (DRE) - a procedure in which the physician inserts a gloved finger into the rectum to examine the rectum and the prostate gland for signs of cancer.
Dilate - relax; expand.
Dilation and curettage (also called D & C) - a surgical procedure in which the cervix is dilated (expanded) so that the cervical canal and uterine lining can be scraped with a curette (spoon-shaped instrument).
Diphtheria - a serious, infectious disease that produces a toxin (poison) and an inflammation in the membrane lining of the throat, nose, trachea, and other tissues.
Diplopia - double vision.
Direct fluorescent antibody test (dFA) - a test most frequently used to diagnose rabies in animals.
Disability - the inability to perform an activity in a normal way as a result of an impairment, such as not being able to walk due to a weakness or paralysis in a leg.
Disk herniation (also called disk prolapse, disk bulge, or slipped disk) - a protruding or bulging of the padded areas, called discs, between the vertebrae in the spine.
Dislocation - occurs when extreme force is put on a ligament causing the two bone ends to separate. Dislocations can also affect a joint, the point where two or more bones come together. The joint is created as a "ball-and-socket" joint. A dislocated joint causes the head of the bone (ball) to partially or completely come out of the socket.
Distention - bloating or swelling; usually referring to the abdomen.
Diuretic - a medication that lowers blood pressure by causing excess fluid to be excreted.
Diverticula - plural form of diverticulum.
Diverticulosis - condition that occurs when small pouches (diverticula) push outward through weak spots in the colon.
Diverticulum - small pouch in the colon. These pouches are not painful or harmful unless they become infected or irritated.
Dizziness - physical unsteadiness, imbalance, and lightheadedness that may be associated with balance disorders.
DMD - Doctor of Dental Medicine; a dentist.
Domestic violence - violence and abuse by family members or intimate partners such as a spouse, former spouse, boyfriend or girlfriend, ex-boyfriend or ex-girlfriend, or date.
Dopa decarboxylase - an enzyme present in the body that converts levodopa to dopamine.
Dopamine - a chemical substance, a neurotransmitter, found in the brain that regulates movement, balance, and walking.
Doppler ultrasound - a procedure that uses sound waves to evaluate heart, blood vessels, and valves.
Ducts - narrow tube structures or channels that carry body fluids. In the breast, ducts transport milk from the lobules to the nipple.
Dumping syndrome (also called rapid gastric emptying) - condition that occurs when food moves too fast from the stomach into the small intestine.
Duodenal ulcer - ulcer in the lining of the first part of the small intestine (duodenum).
Duodenitis - irritation of the first part of the small intestine (duodenum).
Duodenum - the first section of the small intestine.
Durable power of attorney - a legal document denoting a friend or family member as the legal guardian in case a person is unable to make medical decisions for himself/herself.
Dysarthria - group of speech disorders caused by disturbances in the strength or coordination of the muscles of the speech mechanism as a result of damage to the brain or nerves.
Dysentery - infectious disease of the colon; symptoms include bloody, mucus-filled diarrhea, abdominal pain, fever, and loss of fluids from the body.
Dysequilibrium - any disturbance of balance.
Dysfluency - disruption in the smooth flow or expression of speech.
Dysgeusia - distortion or absence of the sense of taste.
Dyskinesia - an involuntary movement including athetosis and chorea.
Dysmenorrhea - pain or discomfort experienced just before or during a menstrual period.
Dysmenorrhea, primary - from the beginning and usually lifelong; severe and frequent menstrual cramping caused by uterine contractions.
Dysmenorrhea, secondary - due to some physical cause and usually of later onset; painful menstrual periods caused by an another medical condition present in the body (i.e., pelvic inflammatory disease, endometriosis).
Dysosmia - distortion or absence of the sense of smell.
Dyspareunia - pain in the vagina or pelvis experienced during sexual intercourse.
Dyspepsia - indigestion.
Dysphagia - difficulty in swallowing.
Dysphonia - any impairment of the voice or difficulty speaking.
Dysplasia - abnormal development of tissue.
Dyspnea - shortness of breath.
Dyspraxia of speech - partial loss of the ability to consistently pronounce words in individuals with normal muscle tone and coordination of the speech muscles.
Dysrhythmia - an abnormal heart rhythm.
Dysthymia (also known as dysthymic disorder) - classified as a type of affective disorder or mood disorder that often resembles a less severe, yet more chronic form of major (clinical) depression. However, people with dysthymia may also experience major depressive episodes at times.
Dystonia - abnormal muscle tone of one or more muscles.
Dystrophin - a protein; a chemical substance made by muscle fibers.