A person who supports the idea of the Symbionment (the organic and symbiotic interconnections of life that we are active participants in), through active engagement with others and creative acts that promote sumbiosity in the form of ecoculture, ecoagriculture, ecotechnologies and ecodesign in all aspects of our lives. Through sumbiosic development, we maintain our connections within the symbionment and help create The Symbiocene.
We have now got rid of some very difficult concepts that are part of the reason why we have failed to achieve the end state we have historically called sustainability.
An environmentalist = no wonder it is a word that generates disagreement in people. There is no such thing as 'the environment' (see below) so there cannot be an environmentalist!