The term ‘mol’, supposedly, was first used in 1895 by German physical chemist Walther Nernst, a truncation of the 1893 term gram-molecule (a term used previously by German physical chemist Wilhelm Ostwald). Nernst also used the term "g-mol" in his introduction of the ideal gas law. 
Etymologically, the term "mol" is said to derive from the German mol, meaning small mass.
● Avogadro’s constant
● Social Avogadro number
1. Daintith, John. (2005). Oxford Dictionary of Science. Oxford University Press.
2. (a) Nernst, Walther. (1895). Theoretical Chemistry: from the Standpoint of Avogadro’s Rule & Thermodynamics. MacMillan and Co.
(b) Ostwald, Wilhelm. (1893). Hand- und Hilfsbuch zur ausführung physiko-chemischer Messungen (Handbook and Support for Making Physico-Chemical Measurements) (pg. 119). Leipzig.
● Mole (unit) – Wikipedia.