a set of instructions, appearing once within a computer program but available for repeated use, for performing a specific task
A set of instructions that performs a specific task for a main routine, requiring direction back to the proper place in the main routine on completion of the task.
sub- +"Ž routine
subroutine - Computer Definition
A group of instructions that perform a specific task. A large subroutine might be called a "module" or "procedure." Subroutine is somewhat of a dated term, but it is still quite valid.