the molecular weight of a substance expressed in grams; the basic unit of amount of substance adopted under the Systeme International d'Unites
"The chemist calculated that exactly one mole of water has a mass equal to its molecular weight in grams."
Alternative spelling of mole
"The scientist noted that the alternative spelling mol was sometimes used in older chemistry texts to represent a mole."
In plain English: A mol is a standard unit used to measure how many particles are present in a specific amount of substance.
"The chemist carefully measured out exactly two moles of salt to mix into her solution."
The word mol was borrowed into English in 1897 directly from the German term of the same spelling. It entered usage to refer to a specific type of chemical reaction without changing its original meaning.