[From the Greek suffixes -ismos: the action of doing something, and from Greek -isma: the result of such action.]
(general) The action or practice of doing something (e.g., terrorism, patriotism).
(general) An instance of a certain kind of action or practice (e.g., witticism, Americanism).
(general) The condition of being a certain way (e.g., barbarism, alcoholism).
(general) A theory, doctrine, movement, or approach in philosophy, religion, politics, science, the arts, or a related discipline. Examples from philosophy include consequentialism, emotivism, Epicureanism, and syncretism.