NM

Nm can refer to several quantities, depending on context. In scientific and technical usage, it most commonly denotes nanometer (symbol nm), newton meter (symbol N·m), or nautical mile (symbol NM). The exact meaning is usually clear from capitalization and the field of use.

Nanometer (nm) is a unit of length in the metric system equal to one billionth of a meter (10^-9 m). The symbol is typically written as nm. Nanometers are used to measure wavelengths of light, molecular and atomic dimensions, and thin-film thicknesses. For perspective, visible light spans roughly 400 to 700 nm, and many biomolecules have dimensions on the order of a few nanometers.

A newton meter (N·m) is the SI unit of torque or moment of force. It is defined as the torque produced by a force of one newton applied at a perpendicular distance of one meter from the pivot. It is the standard unit for rotational moment; it is not a unit of energy, though energy and torque can relate in rotating systems through angular displacement and work.

A nautical mile (NM) is a unit of length used in maritime and aviation contexts. One NM is defined as exactly 1852 meters. Nautical miles are commonly used to express distances over water or air, and speed is measured in knots, which are nautical miles per hour. The symbol NM is widely used on charts and in navigation documentation.

In ambiguous cases, the intended meaning of Nm should be inferred from the field and accompanying quantities.