A subroutine is a small block of code that performs a specific task within a larger program. There are various synonyms for the word subroutine, which is commonly used in computer programming. One such synonym is a procedure, which is a set of instructions that can be called multiple times from different parts of the program. A function is another synonym for a subroutine, which returns a value after performing a specific operation. A method is a subroutine that is associated with an object-oriented programming language, while a module refers to a self-contained program unit that can be reused in different programs. Overall, synonyms for the word subroutine vary depending on the programming language and the specific task at hand.