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A facial expression that may represent pleasure, amusement, derision, or scorn. The corners of the mouth are turned up in an expressions of pleasure or amusement, and the eyes usually appear to be warm and friendly.

Smith fracture

(smith) [Robert W. Smith, Irish physician, 1807–1873] A fracture of the distal end of the radius, with anterior displacement of the fragment.

Smith-Lemli-Opitz syndrome

(smith′lem′lē-ō′pits) [David Weyhe Smith, U.S. pediatrician, 1926–1981; Luc Lemli, Belgian pediatrician, b. 1931; John Marius Opitz, Ger.-born U.S. geneticist, b. 1935] ABBR: SLOS. An autosomal recessive disorder in cholesterol synthesis that results in mental retardation, microcephaly, union of the second and third toes, ambiguous genitalia, weak muscular tone, and other anomalies. SYN: 7-dehydrocholesterol reductase deficiency.

Smith-Petersen nail

(smĭth′pē′tĕr-sĕn) [Marius N. Smith-Petersen, U.S. orthopedic surgeon, 1886–1953] A special nail that on cross-section has three flanges, used for stabilizing fractures of the neck of the femur.


[blend of smoke and fog] Dense fog combined with smoke and other forms of air pollution.


(smōk) Any suspension in the air of particles produced by combustion.

environmental tobacco s. Secondhand s.

first-hand s. Mainstream s.

mainstream s. Smoke released by a burning tobacco product and directly inhaled by the smoker. SYN: first-hand s.

second-hand s. The airborne pollutants released from tobacco smoke into the air, from which they can be inhaled. SYN: environmental tobacco s.; sidestream s.

sidestream s. Second-hand s.

smoke evacuator

A combined vacuum and filter system used intraoperatively to clear the plume of smoke generated by laser or electrocautery.

smoke inhalation injury

SEE: under injury.


One who inhales tobacco smoke or the smoke of other burning materials, e.g., marijuana or hashish.

high-risk s. One who has smoked tobacco products for 30 or more packyears.

smoking ordinance

Any regulation or law that specifies where people may smoke (tobacco products), and where smoking is prohibited.


Of some cancers or infections, developing, growing, or progressing slowly.


subacute myelo-optic neuropathy.


[L. stannum] Symbol for the element tin.


(snal) A small mollusk having a spiral shell and belonging to the class Gastropoda. Snails serve as intermediate hosts of many species of parasitic flukes.

cone s....

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