NM may refer to any of the following:
1. The scientific unit nm is short for nanometer, which is a billionth of a meter. The fabrication process of CPUs is categorized in nm, in reference to the size of the pathways which carry electrical current on the processor's semiconducting silicon. Narrower pathways permit more circuits per chip, higher processing power, and greater energy efficiency.
2. Shorthand for never mind, NM is used in chat rooms and text communications. Never mind may also be abbreviated as NVM.
3. Shorthand for Not Much, NM is another term used in chat rooms.
4. Shorthand for Nothing Much, NM is commonly term used in chat rooms.
5. Shorthand for No Message, NM or N/T (no text) is another term used in chat rooms to let users know that all text is contained in the subject line.