Aft, After:  toward the stern or back of the boat.
Aloft:  overhead.
Backstay:   a wire that supporst the mast; runs from the top of the mast to the stern of the boat.
Battens:  stiffeners that fit into pockets sewn into the aft edge (leech) of a sail; they stiffen the loose edge and provide more usable sail area and a better sail shape.
Beam:  the width of the hull at its widest point.
Boom:  the horizontal spar that is attached to the mast at a right angle to support the bottom of the mainsail.
Boom Vang:  an adjustable rod or tackle that prevents the boom from lifting or dropping on deck.
Bow:  the front of the boat.
Catboat:  the simplest rig, with one mast and one sail.
Centerboard:  used in lieu of a fixed keel, a wood or metal fin that can be lowered vertically through the keel to prevent the boat from slipping sideways in the water, and can also be raised to reduce the boat's draft.
Clew:  the back lower corner of a sail.
Cutter:  similar to a sloop in that there is only one mast, but it is stepped further aft and she can carry two headsails at once (forestaysail and jib).  Often has a bowsprit to enlarge the foretriangle.
Draft:  the depth of water required to float a boat.  Can also refer to the fullness or roundness of a sail.
Foot:  the bottom edge of a sail.  The mainsail foot attaches to the boom; the jib foot is not attached, resulting in it being more difficult to control.
Fore:  toward the front of the boat.
Foretriangle: the area in the sail plan in which the headsail fits.
Genoa (Headsail):   a large jib with an overlap aft of the mast.
Halyard:  line that attaches to the top of a sail and runs down to the bottom of the mast.  Can be internal or external of the mast.
Head:   the top corner of the sail.  Also refers to the toilet on a boat.
Headstay:  wire running from the top of the mast to the boat and to which the jib is attached.  The headstay supports the mast and prevents it from falling backwards.
Hull:  the body of the boat exclusive of the masts, etc.  Includes the bottom, topsides, bouyancy tanks, and deck.
Jib (Headsail):  a sail forward of the mast, attached to the forestay using jib hanks.
Jib Sheet:  consists of two lines connected to the clew of the jib and lead along each side of the boat to the cockpit.
Keel:  the major longitudinal part of a hull.  Also refers to a weighted fin or other member on the bottom of the hull that keeps the boat from slipping sideways in the water.
Ketch:  Similar to a yawl, has 2 masts:  the mainmast and a mizzen mast.  The mizzen mast is generally stepped forward of the rudder post (aft of the rudderpost on a yawl) and the mizzen mast is generally larger than a yawl's mizzen.
Leech:  the back (trailing) edge of a sail.
Leeward:  away from the wind.
Lifelines:  plastic-coated wire rope surrounding the deck to prevent the crew from falling overboard.
Luff:  the front (leading) edge of a sail.  The luff of the mainsail attaches to the mast, and the luff of the jib attaches to the forestay.
Mainsail:  the principal and most easily controlled sail of a boat.  The fore edge is attached along the front of the mast and the bottom edge is attached to the boom.
Mainsheet:   the line used to control lateral position and movement of the mainsail.
Mast:  vertical pole or spar that supports the sails and boom.
Masthead:  the top of the mast.
Port:   the left side of the boat as you face forward.
Reefing:  reducing mainsail area.
Roller-furling:  where a sail is wrapped around its leading edge or luff, similar to a window shade but vertical rather than horizontal.
Rudder:  the flat surface at or near the stern that pivots about a vertical axis to steer the boat.
Running Rigging:  ropes (lines) that pull the sails up and adjust their shape.  Consists of halyards, mainsheet, jib sheets, topping lift, downhaul, outhaul, and cunningham.
Schooner:  a two-masted boat where the aftermost mast is the tallest or all masts are of equal height.  Can also have 3- and 4-masted schooners.
Sheets:  lines used to control a sail's lateral position and movement, as in jibsheet and mainsheet.
Shrouds (Sidestays):  wires that run from the masthead to the sides of the boat to support the mast and prevent it from swaying.
Sloop:   a boat rigged with one mast and two sails (main and headsail or jib).
Spinnaker (Chute):  a colorful, balloonlike sail that is used in downwind sailing.  Usually used in racing.
Standing Rigging:  a collection of wires that supports the mast.  Consists of the headstay, backstay, and shrouds (sidestays).
Stern:  the back of the boat.
Starboard:   the right side of the boat as you face forward.
Tack:  the forward lower corner of a sail.
Tiller:  a wooden or metal steering arm attached directly do the rudderpost and used to turn the rudder.
Topsides:  the sides of the hull between the waterline and the deck.
Traveler:  a slide running across the boat and to which the lower block of the mainsheet is attached.  Used to change the trim of the mainsail by adjusting the slide position.
Trim:  to haul in and tighten up on the sheet attached to a sail or its boom.
Wheel:   steering wheel used to turn the rudder on larger boats in lieu of a tiller.
Windward:  toward the wind.
Yawl:  sailboat with 2 masts, the mainmast and the mizzen mast.  The mizzen mast is usually stepped aft of the cockpit and the rudder post and usually carries a relatively small sail.  Removal of the mizzen mast and its rigging will convert the boat into a sloop.