A movement in literature that attempts to find meaning in a broken world by (a) looking to the past and "making it new" or (b) using the mind to create meaningful order. Modernist literature tends to emphasize the loss of confidence in the present world by showing how it has fallen apart due to war, social injustice, and empty materialism. Although it might seem that Modernist writers are pessimistic and judgmental, they are interested in finding a solution to the predicament and restoring meaning to a world that has lost its way. As a result, this approach to making art often deals with moral concerns, the consequences of bad choices, and philosophical confusion.
Modernist literature also tends to be more difficult, less direct, more experimental than its predecessors. At the same time, the roots of Modernism ARE its predecessors, including Romanticism. Not all Modernist writers are "impossible to understand," such as Robert Frost, but many of them approach this level of difficulty because they are trying to convey how difficult and complex the modern world is, such as Wallace Stevens and T.S. Eliot.
Modernists tends to be preoccupied with meaning: where it comes from, how we make it, and why its important. But they are equally preoccupied with ambiguity, or the uncertainty of meaning.