S

Alphabetical index

A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z

second (plane angle)

Unit of measurement of plane angle, non-SI but accepted for use with SI, symbol: ″.

second (time)

Unit of measurement of time, symbol: s.

SI

The International System of Weights and Measures, agreed in 1960, and since 1995 the UK’s primary system of measurement for most purposes.

siemens

Unit of measurement of electrical conductance, symbol: S.

sievert

Unit of measurement of dose equivalent of radiation, symbol: Sv.

steradian

Unit of measurement of solid angle, symbol: sr.

symbols

Symbols for units are written in a roman font (regular upright) and should not be amended, italicised or pluralised. They are also written lower case, except the symbol L and symbols named after persons e.g. the symbol W for watt named after the Scottish engineer, James Watt.

Symbols for prefixes should be in lower case, except for those meaning a multiple greater than one thousand.

e.g. 3 kilowatts is 3 kW, not 3 Kw or 3 KW or 3 kw, and 500 megawatts is 500 MW.