Definition:  character or combination of characters denoting a unit of measurement
NOTE 1 – Most unit symbols are one or more letters of the Latin or Greek alphabets and are always printed in roman (upright) type and in the same font as the main text. Products of powers of such symbols are used to form the symbols for compound units according to the laws of algebra. In values of quantities, there is a space between the numerical value and the unit symbol, including the degree Celsius (°C) and the percent (%); exceptions are the units degree (°), minute ('), and second (") for plane angles.
NOTE 2 – Internationally adopted unit symbols are given in the BIPM brochure The International System of Units, and in the various parts of ISO/IEC 80000, ISO 31 and IEC 60027.
Examples:
Unit name

Symbol

seconde

s

microampère

µA

ohm

Ω

mètre par seconde carrée

m/s^{2} ou m·s^{−}^{2}

mole

mol

pascal

Pa

