What is abbreviation nautical miles?

Nautical miles (often abbreviated as "nm" or "nmi") is a unit of measurement commonly used in maritime and aviation navigation. One nautical mile is equal to approximately 1.15 statute miles or 1.85 kilometers. It is based on the circumference of the Earth and is defined as one minute of arc along a meridian (line of longitude) of the Earth's surface. Nautical miles are used because they provide a more accurate measure of distance over water and in the air, where the curvature of the Earth affects the distance traveled.