(programming) A no-op; a CPU instruction that does nothing.
1999, Dominic Sweetman, See MIPS RunThe MIPS instruction set is rich in nops, since any instruction with zero as a destination is guaranteed to do nothing.
2004, Patterson et al, Computer Organization and Design: The Hardware/Software InterfaceNotice that in computing CPI or IPC, we do not count any nops executed as useful instructions.