Pronunciation: (iz'um),[key] —n. a distinctive doctrine, theory, system, or practice: This is the age of isms.
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). Cf. -ist, -ize.