- IPA: /ɪzəm/, /ɪzm̩/
- Used to form nouns of action or process or result based on the accompanying verb in -ise or -ize.
- Used to form the name of a system, school of thought or theory based on the name of its subject or object or alternatively on the name of its founder ((when de-capitalized, these overlap with the generic "doctrines" sense below, e.g. Liberalism vs. liberalism)).
- Used to form names of a tendency of behaviour, action, state, condition or opinion belonging to a class or group of persons, or the result of a doctrine, ideology or principle or lack thereof.
- atheism (1587), ruffianism (1589), giantism (1639), fanaticism (1652), theism (1678), religionism (1706), patriotism (1716), heroism (1717), despotism (1728), old-maidism (1776), capitalism (1792), nationism (1798), romanticism (1803), conservatism (1832), sexualism (1842), vegetarianism (1848), externalism (1856), young-ladyism (1869), opportunism (1870), blackguardism (1875), jingoism (1878), feminism (1895), dwarfism (1895)
- Used to form nouns indicating a peculiarity or characteristic of language
- Used to form names of ideologies expressing belief in the superiority of a certain class within the concept expressed by the root word, or a pattern of behavior or a social norm that benefits members of the group indicated by the root word. ((based on a late 20th-century narrowing of the "terms for a doctrine" sense))
- (medicine) Used to form names of conditions or syndromes