Sustainability
Sustainable is any activity that is suitable to last as long as the ecological conditions stay the same. Resource management is sustainable when resources are used up in a speed not higher than their regeneration speed. The expression comes from forestry where it means that only as many trees are cut as can come up in the same time. Fishing is sustainable when the number of fish (of the corresponding species) does not incline. The use of fossil fuels or of nuclear energy is practically never sustainable.
Of course sustainability is a lot older than the word. Many cultures during their history have found a sustainable way of living because unsustainable forms of economy had to come to an end sooner or later.
French: durabilité
