The environmental consequences of mass consumption require to eco-innovate, which means completely rethinking our way of designing, manufacturing and consuming by proposing on the market products and services with a high environmental ambition. In order to help companies in early design phases of eco-innovation, this article investigates the criteria of eco-innovation and tests the understanding of a set of 7 Eco-ideation Stimulation Meso-mechanisms, named ESM. A qualitative experiment based on focus groups and on a case based reasoning approach delivers operable criteria of eco-innovation and redefines at the same time what eco-innovation is. The exhaustive aspect of eco-innovation dimensions to explore covered by the ESM set is confirmed too.