IPA: //sʌbˈruːtiːn//
KK: /sʌbˈruːtin/
A set of instructions in programming that performs a specific task and can be called from other parts of a program.
The programmer wrote a subroutine to handle user input efficiently.
Subroutine → It is formed from "sub-" (meaning under or below) and "routine" (from Old French *routine*, meaning a regular course of action). The word "subroutine" refers to a set of instructions that operates under the main routine, functioning as a smaller part of a larger program.
Think of a 'routine' that operates 'under' ('sub-') the main tasks — that's why a subroutine is a smaller, supporting set of instructions.