Definition of "recursive"

drawing upon itself, referring back.  examples

(mathematics, not comparable) of an expression, each term of which is determined by applying a formula to preceding terms  examples

(computing, not comparable) of a program or function that calls itself  examples

(computing theory, not comparable, of a function) which can be computed by a theoretical model of a computer, in a finite amount of time  examples

(computing theory, not comparable, of a set) whose characteristic function is recursive (4)  examples