According to the Cambridge University Online Dictionary, the noun, sustainability, derived from the Latin sustinere (tenere, to hold; sus, up), is defined as “the ability to continue at a particular level for a period of time.”
In the National Environmental Policy Act of 1969, while not specifically using the word sustainability, Congress directed the government to use “all practicable means and measures … to create and maintain conditions under which man and nature can exist in productive harmony, and fulfill the social, economic, and other requirements of present and future generations of Americans.”
More recently, the most often quoted definition of sustainability and sustainable development comes from the Brundtland Commission of the United Nations in its 1987 Report of the World Commission on Environment and Development: Our Common Future. “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”