ism

UK: /ˈɪzəm/ US: /ˈɪzəm/ ,(iz′əm)

WordReference Random House Learner's Dictionary of American English © 2026

ism /ˈɪzəm/   n. [countable]

1. a distinctive belief, theory, system, or practice;
   anything that could be referred to by a word with the suffix -ism:
   capitalism, socialism, and other isms.

-ism, suffix. 

1. • -ism is attached to verb roots to form action nouns:
     baptize → bapt- + -ism → baptism.
   • -ism is used to form nouns showing action or practice:
     adventure + -ism → adventurism (= the action or practice of taking risks in intervening in international affairs).
   • -ism is used to form nouns showing state or condition:
     alcoholism (= disease or condition in which alcohol is involved).
   • -ism is attached to roots to form nouns showing the names of principles or doctrines:
     Darwinism (= principles of Darwin's theory of evolution); despotism.
   • -ism is used to form nouns showing an example of a use:
     witticism (= example of something witty);
     Africanism (
     = word from Africa or from an African language).

Compare -ist,-ize.

WordReference Random House Unabridged Dictionary of American English © 2026

ism  (iz′əm), n. 

1. a distinctive doctrine, theory, system, or practice:
   This is the age of isms.

• extracted from words with the suffix -ism

-ism, 

1. 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.

• Greek)
• Greek -ismos, -isma noun, nominal suffixes, often directly, often through Latin -ismus, -isma, sometimes through French -isme, German -ismus (all ultimately

Collins Concise English Dictionary © HarperCollins Publishers::

ism / ˈɪzəm/ noun

1. an unspecified doctrine, system, or practice

Collins Concise English Dictionary © HarperCollins Publishers::

-ism suffix:forming_nouns

1. indicating an action, process, or result: criticism, terrorism
2. indicating a state or condition: paganism
3. indicating a doctrine, system, or body of principles and practices: Leninism, spiritualism
4. indicating behaviour or a characteristic quality: heroism
5. indicating a characteristic usage, esp of a language: colloquialism, Scotticism
6. indicating prejudice on the basis specified: sexism, ageism

Etymology: from Old French -isme, from Latin -ismus, from Greek -ismos