Kevlar: A very strong fiber sometimes used for kite lines. Has some characteristics which make it somewhat less desirable than Spectra.
Kitesurfing, Kiteboarding: also called kite sailing or flysurfing. Using a kite to pull you across the water with a board under your feet. Kitesurfing is specific to water. Kiteboarding includes kitesurfing, landboarding and snowkiting.
Knot: speed of one nautical mile per hour. It is 1.852 Km per hour or 1.15 mph.