Adaptive Control System
A System that, as it carries out external Actions and thus gains Feedback from its environment, also carries out internal Actions involving modifying its internals based on its judgments of how it will better achieve its Goals.
(Note: The language of "judgments" used above should not be overinterpreted: this kind of system may be a very simple quantitative system, or else a much more complex sort of system.)
There is a large branch of engineering devoted to adaptive control systems, but nearly all of the theory there is relevant only to specific sorts of adaptive control systems, not including the ones of most relevance to AGI.
Many simple biological organisms are adaptive control systems; this role does not necessarily entail a high degree of Intelligence, but it does entail a nonzero degree of intelligence.
Relationship to Cognitive Development
In the theory of Developmental Stages of Uncertain Logic Based AI Systems, it is hypothesized that in the Concrete Operational Stage, Inference Control becomes an Adaptive Control System.