Until there is a single definition, use this page to navigate through a small sampling of the variety of definitions available from several organizations associated with ecotourism to develop your own.
A definition obtained from Wikipedia but derived from co-founder of the Center for Responsible Travel, Martha Honey in her book, Ecotourism and Sustainable Development, Second Edition: Who Owns Paradise?:
Ecotourism is travel to fragile, pristine, and usually protected areas that strives to be low impact and (often) small scale. It helps educate the traveler; provides funds for conservation; directly benefits the economic development and political empowerment of local communities; and fosters respect for different cultures and human rights.
(Note: This definition is becoming increasingly accepted as the working definition of ecotourism.)
A definition from the Nature Conservancy and the International Union for Conservation of Nature:
Environmentally responsible travel to natural areas, in order to enjoy and appreciate nature (and accompanying cultural features, both past and present) that promote conservation, have a low visitor impact and provide for beneficially active socio-economic involvement of local peoples.Finally, a definition from the International Ecotourism Society:
Responsible travel to natural areas that conserves the environment and improves the well-being of local people.
