a person who is concerned about the natural environment and wants to improve and protect it
NAmE//ɪnˌvaɪərnˈmɛntlˌɪzəm//, NAmE//ɪnˌvaɪrənˈmɛntlˌɪzəm//
noun [uncountable]See environmentalist in the Oxford Advanced Learner's DictionaryCheck pronunciation: environmentalist