noun 1.an expert on environmental problems.
2.any person who advocates or works to protect the air, water, animals, plants, and other natural resources from pollution or its effects.
3.a person who believes that differences between individuals or groups, especially in moral and intellectual attributes, are predominantly determined by environmental factors, as surroundings, upbringing, or experience ( opposed to
hereditarian ).
Origin: 1915–20; environmental +
-ist Related forms en·vi·ron·men·tal·ism, noun
an·ti·en·vi·ron·men·tal·ist, noun, adjective