No contact voltage, an electrical way to detect AC voltage.

What does NCV mean on multimeter?

Built-in Non-Contact Voltage (NCV) Detector allows for quick detection of live voltage.

What is a non-contact voltage?

Non-contact voltage testers work by sensing a very small amount of current that is capacitively coupled from the live circuit to the tester and back to ground. Non-contact voltage testers light up when they detect this current without needing to make direct contact.