1. Shorthand for Never Mind, NM is used in chat rooms and text communications. Never mind may also be abbreviated as NVM.
2. Shorthand for Not Much, NM is another term used in chat rooms.
3. Shorthand for Nothing Much, NM is commonly term used in chat rooms.
4. Shorthand for No Message, NM or N/T (no text) is another term used in chat rooms to let users know that everything has been said in the subject line.
5. NM is also short for nanometer, which is a billionth of a meter.