Dictionary

summer cold See hay fever.

sun protection factor A measurement of a sunscreen’s potency, expressed on a scale from two upward. Abbreviated SPF. Sunscreens with an SPF of 15 or higher provide the best protection from the sun’s harmful rays. See also ultraviolet radiation.

sunscreen A substance that blocks the effect of the sun’s harmful rays. Using lotions that contain sunscreen can reduce the risk of skin cancer, including melanoma. See also ultraviolet radiation.

superaspirin See cox-2 inhibitor.

superficial spreading melanoma See melanoma, superficial spreading.

superior vena cava syndrome A condition in which the large vein that carries blood down to the heart (superior vena cava) is compressed. This compression may be caused by disease of any of the structures or lymph nodes surrounding this vein. Superior vena cava syndrome is characterized by swelling of the face, neck, and/or arms,…

supernumerary Beyond the normal number, extra. For example, a supernumerary chromosome is an extra one beyond the usual number of 46, and a supernumerary digit is an extra finger or toe.

supernumerary placenta See placenta, accessory.

supertaster A person who has an unusually large density of taste buds, each surrounded by pain fibers. As a result, the person has an exquisite ability to taste accurately.

subacute sclerosing panencephalitis A chronic brain disease of children and adolescents that occurs months to often years after an attack of measles and causes convulsions, motor abnormalities, mental retardation, and usually death. Abbreviated SSPE.

subaortic stenosis Narrowing of the left ventricle of the heart, just below the aortic valve, through which blood must pass on its way up into the aorta. The narrowing restricts the flow of blood. Subaortic stenosis may be present at birth (congenital) or acquired as part of a specific form of heart disease known as…

subarachnoid Literally, beneath the arachnoid, the middle of three membranes that cover the central nervous system. In practice, subarachnoid usually refers to the space between the arachnoid and the pia mater, the innermost membrane surrounding the central nervous system. It normally contains cerebrospinal fluid. See also cerebrospinal fluid.