Access Point - a location at the side of a lake or river that you can put your kayak in and out of the water.
Aft - near the back of the boat.
Aground - when a kayak accidentally gets stuck on land or a sandbar.
Astern - describes the back of another kayak.
Backpaddle - paddling backwards to change the direction of the kayak or to slow it down.
Bail - getting water out of your kayak.
Beam - a measurement of kayak width taken at the widest point on a kayak.
Bladder - an inflatable bag put inside a kayak to increase buoyancy when capsized.
Blade - the flat or curved end of a kayak paddle.
Bow - near the front of the boat.
Bulkhead - storage space in the front or back of a kayak (or both).
Capsize - the act of a kayak flipping-over becomming inverted in the water.
Cockpit - the opening in the kayak where the paddler sits.
Deck - the top of the kayak.
Drag - anything preventing the kayak from moving forward.
Face - the part of the kayak blade which pushes the water.
Flatwater - calm water.
Footbrace - a footrest commonly found in sea kayaks.
Hull - the body of a kayak.
Hung Up - when a kayak gets stuck on something like a rock or tree limb.
K1 - a one-person kayak.
K2 - a two-person kayak.
Launch - the act of putting your kayak in the water from shore.
Leeward - moving the opposite direction as the wind.
PFD - a lifejacket is sometimes called a Personal Flotation Device.
Powerface - the part of a kayak paddle that pushes against the water.
Pry Stroke - moving the kayak sideways away from the paddle.
Shaft - the portion of the kayak paddle between the blades, the paddle handle.
Starboard - the right side of the kayak.
Stern - the back of the kayak.
Throat - the portion of a kayak paddle where the shaft and blade meet.
Waterline - the location on the hull of a kayak that water goes up to.
Wet Exit - getting out of a capsized kayak, often when you cannot simply roll out.
Windward - the direction of the wind.
Kayaking.org highly recommends Kayaking Made Easy, a book that will help you master the basic kayaking terminology and techniques.