<P> The knot (/ nɒt /) is a unit of speed equal to one nautical mile per hour, exactly 1.852 km / h (approximately 1.15078 mph). The ISO standard symbol for the knot is kn . The same symbol is preferred by the Institute of Electrical and Electronics Engineers (IEEE); kt is also common . The knot is a non-SI unit that is "accepted for use with the SI". Worldwide, the knot is used in meteorology, and in maritime and air navigation--for example, a vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour . </P> <P> Etymologically, the term derives from counting the number of knots in the line that unspooled from the reel of a chip log in a specific time . </P> <Dl> <Dt> 1 international knot = </Dt> <Dd> 1 nautical mile per hour (by definition), </Dd> <Dd> 1.852 kilometres per hour (exactly), </Dd> <Dd> 0.51444 metres per second (approximately), </Dd> <Dd> 1.15078 miles per hour (approximately), </Dd> <Dd> 20.25372 inches per second (approximately) </Dd> <Dd> 1.68781 feet per second (approximately). </Dd> </Dl>

Where does the nautical term knots come from