Definition: mnemonic

Pronounced "ni-mon-ic." A memory aid. In programming, it is a name assigned to a machine function. For example, COM1 is the mnemonic assigned to serial port #1 on a PC. Programming languages are almost entirely mnemonics. For example, in x86 assembly language, CMP is used to represent the "compare" instruction and JE for "jump if equal."

Not Just for High Tech
Mnemonics have been used as verbal tricks to help people remember just about anything. For example "30 days hath September, April, June and November, etc." is a mnemonic rhyme. "Roy G. Biv" spells out the colors of a rainbow: red, orange, yellow, green, blue, indigo and violet.