Definition:Mole

Mole
The mole is the SI base unit of amount of substance.

It is defined as exactly $6 \cdotp 02214 076 \times 10^{23}$ particles.

The specific type of particle under discussion must be specified.

They usually include:
 * atoms (of a specified element)
 * molecules (of a specified substance)
 * ions (of a specified type)
 * electrons
 * photons

and so on, but (as long as the particles are more-or-less identical), there is no specific limitation to what a mole may be applied to.

A beloved teacher of chemistry at a certain editor's school, when covering the subject, would habitually spend some time discussing a mole of cricket balls.

Also known as
Terms formerly used for a mole include:
 * gram-molecule (for a substance whose elementary entities are molecules)
 * gram-atom (for a substance whose elementary entities are atoms)