<span>The knot (/nɒt/) is a unit of speed equal to one nautical mile (1.852 km) per hour, approximately 1.151 mph. The ISO Standard symbol for the knot is kn. The same symbol is preferred by the IEEE; kt is also common.</span>
The speed of a vessel in comparision with the fluid so its basically a measure of speed, for eg in boats its boat speed, and in aeroplanes,aircrafts etc its air speed. hope it helped... :)
