Mnemonic is an adjective that describes something related to or assisting in memory.
A mnemonic device is a tool or technique that helps someone remember something, such as a phrase, acronym, or image.
Here are some examples:
* "ROYGBIV" is a mnemonic for the colors of the rainbow (Red, Orange, Yellow, Green, Blue, Indigo, Violet).
* "Every good boy deserves fudge" is a mnemonic for the notes on the lines of the treble clef (E, G, B, D, F).
So, when someone uses "pnemonic", they are likely trying to refer to "mnemonic" which relates to memory aids.