Here's a breakdown:
* Noun: This is the most common function of words ending in "-ism." They usually represent a doctrine, belief, theory, practice, or system of thought or action.
* Examples: capitalism, socialism, feminism, racism, Buddhism
* Adjective: Sometimes "-ism" words can function as adjectives, describing a noun or pronoun.
* Examples: realistic, optimistic, pessimistic
* Verb: While less common, some words ending in "-ism" can be verbs, particularly those related to performing an action or adopting a particular belief.
* Examples: to criticize, to economize, to moralize
It's important to consider the context in which the word is used to determine its part of speech.