Abeam: at right angles to the boat.
Aft: toward the stern; opposite of forward.
Back: to trim a sail windward so that it fills with wind backward
Backstay: the support wire between the top of the mast and the back of the boat
Bear away: to turn away from the wind (or to turn to leeward).
Bearing: the angle to an object measured in compass or relative degrees.
Boom: the horizontal pole that supports the bottom edge of the mainsail.
Bow: the front of the boat.
By the lee: sailing downwind with the wind coming over the same side of the boat as the boom is trimmed, which can cause an accidental jibe.
Clew: the aft, bottom corner of a sail.
Close-hauled: the closest course to the wind that you can effectively sail. Also called sailing upwind, on the wind or beating.
Cockpit: the area where the crew sits to operate the boat.
Deck: the top of the hull.
Downwind: (1) a run, but can mean any point of sail when the wind is aft of the beam (2) the direction the wind is blowing toward.
Flight: a group or series of races
Foot: (1) the bottom edge of a sail. (2) to sail slightly lower than close-hauled in order to go faster.
Forestay: the support wre that runs from the mast down to the bow.
Genoa: a large jib that overlaps the mast.
Grommet: a small plastic or metal ring pressed or sewn into a sail, creating a hole.>
Head: the top corner of any sail.
Head up: to turn the boat toward the wind (or windward).
Heavy air: strong winds.
Helm: (1) the wheel or tiller - the steering device. (2) A technical word for the balance of forces on the rudder. (3) the position of the helmsman on the boat.
Helmsman: the driver or skipper of the boat.
Hull: the body of the boat.
Jib: the most common headsail.
Jibe: to change tacks by turning away from the wind.
Keel: A fixed, ballasted center fin that keeps the boat from sideslipping and provides stability to prevent capsizing or tipping over.
Knot: (1) nautical mile (6,076 feet) per hour.
Layline: the line beyond which you can lay (make) the destination on a close-hauled course with no more tacks.
Leech: the back edge of a sail.
Leeward: downwind; away from the wind.
Luff: (1) the front edge of a sail from the head to the tack. (2) The flapping motion of sailcloth when a sail is undertrimmed (or not trimmed at all).
Mainsail: the aft-most sail on a boat with one mast, normally attached to the mast along its front edge.
Mainsheet: the adjustment rope that pulls the boom (hence the mainsail) in and out.
Mast: the vertical pole that supports sails.
No-sail zone: Zone where a sailboat can't sail; about 90 degrees wide, with the center point being toward the true wind direction.
Port tack: Sailing with the wind coming over the left side of the boat.
Puff: An increase in wind velocity.
Rig: (1) the mast and standing rigging. (2) a term for preparing the boat (or sail or fitting) for use.
Round Robin: A round-robin tournament (or all-race-all tournament) is a competition "in which each contestant meets all other contestants in turn".
Rudder: the underwater fin that steers a boat; controlled by a tiller or wheel on deck.
Sheet: the primary line that adjusts the sail's trim. Usually referred to with the sail it adjusts, as in, "Pull in the mainsheet."
Spinnaker: a big, colorful, parachute-like specialty sail used when sailing downwind.
Standard rigging: all the wires that support the mast, including the forestay, shrouds and backstay.
Starboard tack: sailing with the wind coming over the boat's right side.
Stern: the back end of the boat.
Tack: (1) the front, bottom corner of a sail. (2) the boat's heading in relation to the wind (that is on starboard or port tack) (3) to change tacks by turning toward the wind, entering the no-sail zone from one side and exiting on the other.
Tiller: the lever arm that controls the position of the rudder.
Tiller extension: a device attached to the end of the tiller that enables a person to sit farther outboard while steering.
Trim: (1) to pull in a rope or a sail. (2) the set of sails. (3) the bow-up or bow-down position of the boat when not moving.
Windward: toward the wind; the side the wind blows upon.
Wing the jib: when sailing on a run, to trim the job on the opposite side as the mainsail.
Source: The wmrt match racing glossary.