Shamelessly stolen from wikipedia.
Capitalism: Capitalism is an economic system structured upon the accumulation of capital in which the means of production are privately owned and operated for profit, usually in competitive markets. Income in a capitalist system takes at least two forms, profit on the one hand and wages on the other. There is also a tradition that treats rent, income from the control of natural resources, as a third phenomenon distinct from either of those. In any case, profit is what is received, by virtue of control of the tools of production, by those who provide the capital. Often profits are used to expand an enterprise, thus creating more jobs and wealth. Wages are received by those who provide a service to the enterprise, also known as workers, but do not have an ownership stake in it, and are therefore compensated irrespective of whether the enterprise makes a profit or a loss.
Consumerism: Consumerism is a social and economic order that is based on the systematic creation and fostering of a desire to purchase goods and services in ever greater amounts. The term is often associated with criticisms of consumption starting with Thorstein Veblen. Veblen's subject of examination, the newly emergent middle class arising at the turn of the twentieth century, comes to full fruition by the end of the twentieth century through the process of globalization.
Commercialism: The tendency within open-market capitalism to turn everything into objects, images, and services sold for the purpose of generating profit. There is also a tendency for intangible things such as happiness, beauty, or health to be given a monetary value (monetization) and to be spoken of as commodities.
Modernity: Modernity typically refers to a post-traditional, post-medieval historical period, one marked by the move from feudalism (or agrarianism) toward capitalism, industrialization, secularization, rationalization, the nation-state and its constituent institutions and forms of surveillance. Conceptually, modernity relates to the modern era and to modernism, but forms a distinct concept. Whereas the Enlightenment invokes a specific movement in Western philosophy, modernity tends to refer only to the social relations associated with the rise of capitalism. Modernity may also refer to tendencies in intellectual culture, particularly the movements intertwined with secularisation and post-industrial life, such as Marxism, existentialism, and the formal establishment of social science. In context, modernity has been associated with cultural and intellectual movements of 1436—1789 and extending to the 1970s or later.
Modernism: Modernism, in its broadest definition, is modern thought, character, or practice. More specifically, the term describes the modernist movement, its set of cultural tendencies and array of associated cultural movements, originally arising from wide-scale and far-reaching changes to Western society in the late 19th and early 20th centuries.
Modernism was a revolt against the conservative values of realism. Arguably the most paradigmatic motive of modernism is the rejection of tradition and its reprise, incorporation, rewriting, recapitulation, revision and parody in new forms. Modernism rejected the lingering certainty of Enlightenment thinking and also rejected the existence of a compassionate, all-powerful Creator God.