Dictionary

Enter a word or phrase below to search our online dictionary of over 1,300 general medical terms, or click on a letter of the alphabet to view all terms beginning with that letter:

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Search for 'S'

Phrase Definition
sac Pouch; a bag-like structure.
saccharin A compound that's hundreds of times sweeter than table sugar. Used as an artificial sweetener.
sacroiliac Having to do with the joint formed by the sacrum and the ilium in the lower back.
saliva An enzyme-containing thin, watery secretion of the salivary glands.
salivary gland Any one of the three pairs of glands of the mouth (parotid, submaxillary and sublingual) that release saliva.
salmonella A form of food poisoning characterized by fever and intestinal disorder due to Salmonella bacteria.
salve Ointment.
sanguineous Bloody.
scabies An itchy, contagious skin condition caused by mites.
scapula The shoulder blade.
scarlet fever Fever and skin reaction caused by certain strains of streptococcus bacteria, usually following a streptococcal infection of the throat, middle ear or skin.
schizophrenia A chronic mental disorder characterized by an inability to differentiate reality from fantasy. Often associated with hallucinations or delusions.
sciatica Pain or inflammation going from the back to the buttock along the sciatic nerve.
sclera The tough white covering of the eyeball.
scleritis Inflammation of the sclera, causing pain, redness and possible loss of vision. Can be a complication of rheumatoid arthritis.
scleroderma A chronic disease characterized by hardening or thickening of the skin due to abnormal tissue growth.
sclerosis Hardening.
scotoma A blind spot in an area of otherwise normal vision.
scratch test A test for allergies in which small amounts of potential allergens are inserted in small scratches made in the skin.
scrotum The skin-covered sac that contains the testes.
scurvy A condition caused by vitamin C deficiency. Symptoms include loss of appetite, bleeding gums, bruising, inability to gain weight and irritability.
sebaceous cyst A benign cyst containing oil and cells from a sebaceous gland.
sebaceous glands Small glands in the skin that release an oily substance through the hair follicles.
seborrhea Greasy scales or cheesy plugs resulting from overproduction of the sebaceous glands.
seborrheic keratoses Skin growths that may be smooth or warty-looking, of varying size, and flesh-colored, brown or black. Often appear on the trunk or temples. Often occur in middle-aged and elderly people. Also called senile warts.
seizure An attack of epilepsy.
semen The ejaculate of the male consisting of sperm and secretions from the prostate, seminal glands and other glands.
semicircular canals The three loop-shaped tubular passages of the inner ear that control the sense of balance.
seminiferous Carrying or producing semen.
sensorium The state of a person's mental awareness.
sepsis When disease-causing bacteria from an area of infection spread into the bloodstream and tissues.
septum A wall dividing an organ or cavity, as in the nose.
serology The study of the antigen-antibody reaction.
serotonin A chemical used to transmit information from one nerve cell to another.
serum The clear, yellowish-colored liquid portion of blood.
shigellosis A diarrheal disease caused by Shigella bacteria.
shingles A viral infection of certain sensory nerves that causes pain and blisters on the skin along the course of the infected nerve. Also called herpes zoster.
shock A disorder resulting from disruption of the circulation of the blood that can upset all body functions.
shoulder The ball-and-socket joint connecting the arm with the body.
shunt To surgically divert the flow (such as of blood) from one organ or pathway to another.
Siamese twins Identical twins born joined together.
sickle cell anemia A genetic condition characterized by abnormal red blood cells containing a defective form of hemoglobin. Sickle cell anemia occurs in people who inherit the gene from both parents. Found chiefly in black populations and causes anemia, jaundice and recurring attacks of fever and pain in the arms, legs and abdomen.
sickle cell trait Inheriting the gene for sickle cell anemia from only one parent. It causes no symptoms.
sigmoid S-shaped.
sinew A tendon or fibrous cord.
sinus A cavity in a bone or other tissue. Commonly used to describe the cavities in the skull that open into the nasal cavity.
sinusitis Inflammation and infection of the sinuses.
sitz bath A bath in which only the hips and buttocks are immersed in water for relief of rectal or vaginal discomfort.
skeleton The hard bony framework of the human body that supports the tissues and protects the organs.
skull The bony framework of the head.
smallpox A viral disease that was once highly contagious. Characterized by high fever, vomiting, and blisters and sores on the skin. Vaccination has eliminated this disease.
smooth muscle A type of muscle tissue controlled by the involuntary nervous system, occurring in the walls of the uterus, intestines or blood vessels.
sneeze To exhale breath from the nose and mouth in a sudden, involuntary action as a result of irritation of the mucous membranes of the nose.
Snellen's chart A chart of block letters used to test distant vision.
snoring Harsh breathing sounds during sleep caused by the vibration of the soft palate during inhalation.
soft palate The soft part of the roof of the mouth in the back, toward the throat.
soft tissue The substance of an organic body or organ consisting of cells and intercellular materials. The muscles and other nonbony tissues of the body.
solar plexus The network of nerves in the center of the abdomen.
spasm A sudden, involuntary contraction of a muscle or group of muscles.
specimen A sample taken to study the nature of the whole.
speculum An instrument for opening a body cavity to permit visual inspection.
sperm The male germ cell. Also called spermatozoon.
sphincter A ring-shaped muscle that surrounds a natural opening in the body and can open or close it by relaxing or contracting.
sphygmomanometer An instrument for measuring blood pressure. An inflatable blood-pressure cuff.
spina bifida A birth defect caused by imperfect closure of part of the spinal column, exposing some of the nervous system.
spirochete Spiral-shaped bacteria.
spleen The blood-forming and -storing organ located under the ribs in the upper left portion of the abdomen.
splenomegaly Enlargement of the spleen.
splint A device for holding broken or injured parts in place.
spondylitis Inflammation of the vertebrae.
spondylosis Narrowing of the spinal column resulting in reduction of the spaces between the vertebrae which may cause compression of the nerve roots.
sprain A twisting or stretching injury of a ligament or muscle of a joint, with or without dislocating a bone.
spur A projecting body. For example, from a bone.
sputum Mucus secreted by the lungs, bronchi and trachea that's ejected by coughing or clearing the throat.
stapedectomy Surgical removal of the stapes.
stapedioplasty Replacement of the stapes with other materials (wire, bone, plastic).
stapes A small bone of the middle ear. Also called the stirrup.
stenosis Narrowing of a body passage or opening.
sterile 1. Free from living microorganisms. 2. Unable to have children.
sternum The breastbone.
Stevens-Johnson reaction An inflammatory disease characterized by rapid attack of fever, skin blisters and sores on the lips, eyes, mouth, nasal passage and genitals.
stoma 1. Mouth-like opening. 2. An opening used for drainage.
stomatitis Inflammation of the mucosa of the mouth.
stool Feces, or bowel movement.
strabismus A deviation in which both eyes aren't trained on the same spot. Also called crossed eyes or lazy eye.
strain 1. To filter. 2. Excessive effort. 3. Overstretching a portion of a muscle. 4. Within a species, a group of organisms characterized by a particular trait or quality.
stress 1. Pressure; strain. 2. Any condition that causes mental or physical strain or tension.
stridor A harsh or squeaky sound in breathing, often associated with a blocked larynx.
stroke Deprivation of the blood supply to the brain due to blockage of a blood vessel. Results in unconsciousness, paralysis or other neurologic symptoms.
stye Infection of one of the sebaceous glands of the edge of the eyelid.
subcutaneous Just beneath the skin.
subdural Beneath the dura mater, the covering of the brain.
subliminal Below the threshold of conscious awareness.
subluxation Partial dislocation.
subungual Beneath a nail.
sucrose A natural sugar obtained from sugar cane and sugar beets used as a sweetening agent. Also called table sugar.
suicide Taking one's own life.
sunburn A skin inflammation caused by prolonged exposure to ultraviolet radiation from the sun, tanning beds or other sources.
sunstroke A serious failure of the body's heat-regulating mechanism resulting from excessive exposure to intense heat. Also called heat stroke.
superinfection Sudden growth of a different type of bacteria than the type originally diagnosed and treated. This is a common cause of treatment failure because the new type of bacteria is often resistant to first-line antibiotics.
suppository A cone-shaped solid mass of medication designed to be placed in the rectum or vagina.
surfactant A substance produced in the lungs that reduces surface tension and helps keep the small air sacs open.
surrogate A substitute.
suture 1. The joining together of certain vertebrate bones, especially of the skull. 2. A stitch or stitches made to close a wound. 3. The material used in closing a wound with stitches.
synapse The tiny space between two nerve cells that allows the transmission of a nerve impulse.
syncope Fainting.
synergism The working together of different organs or parts of the body so that their combined action is greater than their individual effects.
synovia The clear lubricating fluid produced in joints, bursae and tendon sheaths.
syphilis A sexually transmitted disease caused by the spirochete Treponema pallidum.
systole The cardiac contraction of a heartbeat.
systolic Systolic blood pressure is the pressure when your heart is contracting, squeezing blood out.