What is a knot a measure of?

A knot is a specific unit of measurement used to express speed, particularly in aviation and maritime contexts. It is equivalent to one nautical mile per hour, which is approximately 1.15 miles per hour or about 1.85 kilometers per hour. This unit is particularly valuable in these fields because it relates directly to navigation over the Earth's surface, where distances are commonly measured in nautical miles. The use of knots allows pilots and mariners to communicate speed in a way that is relevant to the curvature of the Earth and the distances they travel over water or through the air. Other options like temperature, distance, or weight do not align with the definition and application of a knot in this specialized context.