Arcology (short for Architectural Ecology) is a term used to describe a self-sustaining colony, typically a massive building which does not need to import or export supplies to stay running and maintain a population of humans.
The most famous arcology is the SCIRE, due to its presence in Seattle and its catastrophic shutdown. Other commonly known arcologies include the off-shore arkoblocks built by Proteus AG and the Yamatetsu Saotome AquaDomes.
A true arcology is self-sustaining, and needs no outside influence to maintain itself. However, many offshore, deep space, and other colonies are often referred to as arcologies due to their similarities to true arcologies.