abstract expressionism

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A school of painting that flourished after World War II until the early 1960s, characterized by the view that art is nonrepresentational and chiefly improvisational.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun usually capitalized Alternative form of Abstract Expressionism.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a New York school of painting characterized by freely created abstractions; the first important school of American painting to develop independently of European styles