debridement - the surgical removal of foreign material and/or dead, damaged, or infected tissue from a wound or burn.

decibel - unit that measures the intensity or loudness of sound.

deciduous teeth - also known as "baby" or primary teeth.

defecation - passage of bowel contents through the rectum and anus.

defecography - x-ray of the anus and rectum to see how the muscles work to move stool.  

defibrillator - an electronic device used to establish normal heartbeat.

delayed gastric emptying - gastroparesis.

delusions - a condition in which the patient has lost touch with reality and experiences hallucinations and misperceptions.

dendrite - a thread-like extension from a nerve cell that serves as an antenna to receive messages from the axons of other nerve cells.  

dental implants - small dental appliances that are inserted into the upper and lower jaws to help restore a mouth that has little or no non-restorable teeth. 

dental pulp - the soft tissue around 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.

depth perception - the ability to distinguish objects in a visual field.

dermatopathology - the study of the skin in diagnosing skin diseases.

descending colon - the middle part of the colon located on the left side of the abdomen.

diagnosis - identifying a disease by its signs, symptoms, and laboratory findings.

diaphragm - primary muscle used for respiration, located just below the lung bases.

diastolic blood pressure - the lowest blood pressure measure in the arteries, which occurs between heartbeats.

diathermy machine - a piece of equipment used in the operating room to control bleeding.

digestants - medicines 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 break down foods into chemical components that the body can absorb and use for energy, and for building and repairing cells and tissues. 

digital rectal exam (DRE) - 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 (D & C) - a common gynecological surgery which consists of widening the cervical canal with a dilator and scraping the uterine cavity with a curette.

diplopia - double vision.

disc herniation (Also called disc prolapse, disc bulge, or slipped disc.) - disruption to the normal integrity of the intervertebral disc.  

distention - bloating or swelling of the abdomen. 

diuretic - a medication that lowers blood pressure.

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.  

dopamine - a chemical substance, a neurotransmitter, found in the brain that regulates movement, balance, and walking. 

dumping syndrome (Also called rapid gastric emptying.) - condition that occurs when food moves too fast from the stomach into the small intestine.

dysarthia - 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.

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 - an abnormality of growth.

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.

dystonia - a slow movement or extended spasm in a group of muscles.

dystrophin - a protein found in normal muscle tissue.