ism

a suffix appearing in loanwords from Greek, where it was used to form action nouns from verbs ( baptism ); on this model, used as a productive suffix in the formation of nouns denoting action or practice, state or condition, principles, doctrines, a usage or characteristic, devotion or adherence, etc. ( criticism; barbarism; Darwinism; despotism; plagiarism; realism; witticism; intellectualism ).