recursion (or rewriting): a recursive formula iterates an operation using the result of the previous operation as the starting point for the subsequent one.
Fractals are often defined by a recursive formula.
This is also the definition of feedback.
The logistic equation proposed by the mathematical ecologist Robert May 4x(1-x) (verify this) is a classic recursive equation with chaotic output. In this case 1-x is the feedback loop of the effects of overcrowding on a population.
In the "sciences of complexity," Newtonian study of units and the mechanisms that bind them into larger groups is replaced by the study of recursive symmetries between different levels of a system.
when applied to language, recursion refers to the ability to make unbounded use of finite means. The Derridean concept of Mise en Abyme is a recursive mirroring.