Hennepin (Environmentalism: here are entered materials on "concern with the environment, especially with the effects of uncontrolled pollution of the atmosphere.")

Third Barnhart dict. of new English (environmentalism: the interests and activities of environmentalists; concern with the quality of the environment, especially with the effects of uncontrolled pollution of the atmosphere)

Oxford dict. of new words (environmentalism: concern with, or support for, the preservation of the environment)

LC database, Sept. 20, 2005 (environmental movement)