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).
Origin of -ism
< Greek -ismos, -isma noun suffixes, often directly, often through Latin -ismus, -isma, sometimes through French -isme, German -ismus (all ultimately < Gk)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for -ism
suffix forming nouns
indicating an action, process, or resultcriticism; terrorism
indicating a state or conditionpaganism
indicating a doctrine, system, or body of principles and practicesLeninism; spiritualism
indicating behaviour or a characteristic qualityheroism
indicating a characteristic usage, esp of a languagecolloquialism; Scotticism
indicating prejudice on the basis specifiedsexism; ageism
Word Origin for -ism
from Old French -isme, from Latin -ismus, from Greek -ismos
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Medicine definitions for -ism
Action, process; practice:vegetarianism.
Characteristic behavior or quality:puerilism.
State; condition; quality:senilism.
State or condition resulting from an excess of something specified:strychninism.
Doctrine; theory; system of principles:Darwinism.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.