Well, this was new to me. (from wikipedia)
Adhocracy is a type of organization that operates in opposite fashion to a bureaucracy. The term was first popularized in 1970 by Alvin Toffler, and has since become often used in the theory of management of organizations (particularly online organizations), further developed by academics such as Henry Mintzberg.
Robert H. Waterman, Jr. defined adhocracy as “any form of organization that cuts across normal bureaucratic lines to capture opportunities, solve problems, and get results”. For Henry Mintzberg, an adhocracy is a complex and dynamic organizational form. It is different from bureaucracy; like Toffler, Mintzberg considers bureaucracy a thing of the past, and adhocracy one of the future. When done well, adhocracy can be very good at problem solving and innovations and thrives in a changing environment. It requires sophisticated and often automated technical systems to develop and thrive.
Characteristics of an adhocracy:
* highly organic structure
* little formalization of behavior
* job specialization based on formal training
* a tendency to group the specialists in functional units for housekeeping purposes but to deploy them in small, market-based project teams to do their work
* a reliance on liaison devices to encourage mutual adjustment within and between these teams
* low standardization of procedures
* roles not clearly defined
* selective decentralization
* work organization rests on specialized teams
* power-shifts to specialized teams
* horizontal job specialization
* high cost of communication (dramatically reduced in the networked age)
* culture based on non-bureaucratic work 
All members of an organization have the authority within their areas of specialization and in coordination with other members to make decisions and to take actions affecting the future of the organization. There is an absence of hierarchy.
There’s more of course, and a moveable feast, since it’s wikipedia…