An Etymological Dictionary of Astronomy and Astrophysics

A suffix denoting several senses, including state or condition, devotion or adherence, principle, doctrine, act, process.

Etymology (EN): From Gk. -ismos, -isma noun suffixes, often directly, often through L. -ismus, -isma, sometimes through Fr. -isme,
Ger. -ismus (all ultimately from Gk.); → -ist.