Rudder - A spade-like object at the back of the boat that steers the boat by deflection of the water.
Tiller - The lever that controls the rudder.
Winches - A mechanical device used to increase pulling power on a line. (purchase)
Fairleads - Eyes or blocks that guide lines in a desired direction. Usually they are used for jibsheets.
Gooseneck - The fitting that connects the boom to the mast. It works like a swivel allowing the boom to move up and down and swing from side to side.
Keel - The weighted fin at the bottom of the boat that keeps the boat from slipping sideways through the water.
Bow - Front end of the boat.
Stanchions - Vertical posts that hold lifelines in place.
Pulpit - Safety rail at the bow of the boat.
Stern - Back end of the boat.
Port - The left side of the boat when facing forward.
Starboard - The right side of the boat when facing forward.

Basic Standing Rigging
Mast - The large vertical spar that supports the sail and boom.
Boom - The horizontal spar used to hold and extend the foot of the main sail.
Forestay - The wire (cable) that supports the mast from the bow and prevents the top of the mast from moving aft.
Backstay - The wire that supports the mast from the stern and prevents the top of it from moving forward.
Shrouds - The wires that support the mast from the sides and prevent it from moving athwartships. (sideways)
Turnbuckle - Device for adjusting tension on shrouds and stays.
Chainplate - Fitting that connects shrouds to hull.
Tang - Fitting that connects shrouds to mast.

Basic Running Rigging
Halyards - Lines or wire rope used to hoist the sails.
Sheets - Lines used to control the sails. Trimming is tightening the sheet to move the sail towards the centerline of the boat and easing is letting it out.
Outhaul - Line used to tighten or tension the foot or bottom edge) of the sail.
Downhaul - Line used to tighten or tension the luff (forward edge) of the sail.
Boom Vang - Line used to pull the boom down. It prevents the boom from lifting which causes the top part of the sail to twist.
Topping Lift - Holds the end of the boom up and prevents it from falling into the cockpit when the main sail is lowered.

Basic Sail Terms
TERMS APPLYING TO BOTH MAIN AND JIB SAILS
Head - Top corner. (Where halyard connects to sail)
Tack - Bottom forward corner.
Clew - Bottom back corner.
Luff - Forward edge.
Foot - Bottom edge.
Leech - Backedge.
Cringle - Metal reinforcement ring.

TERMS THAT USUALLY APPLY TO MAIN SAILS
Battens - Wood or plastic strips that act as stiffeners for the sail. They help keep the leech from fluttering.
Batten Pockets - Pockets sewn into the trailing edge of the sail to hold the battens.
Roach - The unmeasured Sail area along the back edge of the Sail.
Cunningham - The cringle (grommet) on the luff of the sail used to achieve luff tension for draft control. (sail shaping)
Reef Points - The row of points where the reef ties (gaskets) are attached to the sail.

SAILING TERMS UNDERWAY
Tacking - Turning the bow of the boat through the eye of the wind.
Gybing - Turning the stern of the boat through the eye of the wind.
Luffing - The fluttering of a Sail when a boat is pointed too close to the wind or the sail is eased out too far.
In Irons - The condition when the boat is pointed directly into the wind without steerageway.
Windward - The direction from which the wind is coming.
Starboard Tack - When the starboard side of the boat is windward.
Port Tack - When the port side of the boat is windward.
Leeward - The direction to which the wind is going.
Head Up - Turning the bow of the boat towards the eye of the wind.
Bearing Away - Turning the bow of the boat away from the eye of the wind, also referred to as bearing off or falling off
Helms-A-Lee - Notification that the tiller has been put to leeward to cause the boat to come about. (tacking)

ADDITIONAL SAILING TERMS
Trim - To pull in... as in trim a sheet. (line)
Ease - To let out... as in ease a sheet. (line)
Overtrim - A condition where the sail is trimmed in too tightly for the wind direction.
Undertrim - A condition where the sail is trimmed too loosely for the wind direction. The Sail will luff if undertrimmed more than a slight amount.
Beat - Sailing to windward by means of a Series of tacks.
Reefing - Reducing the area of a sail due to strong wind.
True Wind - The wind speed and direction as seen by a stationary observer.
Apparent Wind - The wind speed and direction as seen by an observer who is moving across the water.
Weather Helm - The tendency of a sailboat to head into the wind if the helm is released. (letting go of the tiller)
Lee Helm - The tendency of a sailboat to head away from the wind if the helm is released.
Header - Change in wind direction towards the bow of the boat.
Lift - Change in wind direction towards the stern of the boat. A header for a boat on port tack is a lift for a boat on starboard tack.
Beam - The widest section of a boat, generaily across the middle.
Abeam - The direction to either side of the boat. (90 degrees from the bow)
Underway - When the boat is neither at anchor, made fast or aground.
No Way - When the boat is stopped.