Definition: Subseptuple is a type of programming language that is specifically designed for implementing subprogrammable data structures. It was created by Robert J. Schneier and is based on the idea that a subprogram can be used to create new program elements, such as subprograms or subexpressions. Subseptuples are often used in compiler-based languages like C++, where they allow for the creation of small programs that can be executed independently of the main program.