A search through Wikipedia provides the following definitions of sustainability:
Sustainability: in a general sense, is the capacity to maintain a certain process or state indefinitely.
Sustainable development: is a pattern of resource use that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but in the indefinite future. The term was used by the Brundtland Commission, which coined what has become the most often-quoted definition of sustainable development as development that "meets the needs of the present without compromising the ability of future generations to meet their own needs."[1]
The field of sustainable development can be conceptually broken into three constituent parts: environmental sustainability, economic sustainability and sociopolitical sustainability.
Presentation by Peter Willis "Turbulent Future" - July 2009
(1MB PDF)
The growing need for expanded corporate reporting
(85KB PDF)
SAICA has developed literature on Sustainability
(2.7MB PDF)
Link to SAICA's Sustainability website
http://www.saica.co.za/sustainability/