True en.vi.ron.men.tal.ist (troo en vi'ren ment'list) noun. 1. Someone who is willing to tone down their lifestyle in a conscious effort to return to a more "environmentaly benign" existence. 2. An individual or individuals who leave a small carbon footprint. 3. Someone who is a net contributor to aggregate planetary "beneficial" biomass rather than a net substractor from it. 4. Someone who lives modestly; nor is obsessed by the accumulation of "things".