9f7dbe57__units___UK_Metric_Association_SI_base_units_it_measures_and_its_definition
[Unit name] mole [Symbol] mol
Amount of a substance Used in chemistry and physics. It represents a fixed number of "elementary entities" of a substance. When the mole is used, the elementary entities must be specified. Those entities may be atoms, molecules, ions, electrons or any groups of particles so long as they are all the same. The amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12.
Base units | UK Metric Association
What it measures and its definition