Abeam - the direction to either side of the boat (90 degrees from the bow).

Apparent Wind - the wind speed and direction as seen by an observer who is moving across the water.

Bearing Away- turning the bow of the boat away from the eye of the wind, also referred to as bearing off or falling off.

Beating - sailing to windward by means of a series of tacks.

Beam - the widest section of a boat, generally across the middle.

By the Lee - sailing so that the wind is on the same side as where the main is carried. When running, this could happen if there is a wind shift to the side of the boat where the main is. Sailing by the lee is discouraged because it could result in an accidental Gybe

Ease - to let out... as in ease a sheet (line).

Gybing - turning the stern of the boat through the eye of the wind.

Head-Up - turning the bow of the boat towards the eye of the wind.

Helms-A-Lee - notification that the tiller has been put to leeward to cause the boat to come about (tacking).

Header - change in wind direction towards the bow of the boat.

In Irons - the condition when the boat is pointed directly into the wind without steerageway. In the no-go zone.

Lee Helm - the tendency of a sailboat to head away from the wind if the helm is released.

Leeward - the direction to which the wind is going.

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.

Luffing - the fluttering of a sail when a boat is pointed too close to the wind or the sail is eased out too far.

No Way - when the boat is stopped.

Over trim - a condition where the sail is trimmed in too tightly for the wind direction.

Port Tack - when the port side of the boat is windward.

Reefing - reducing the area of a sail due to strong wind.

Starboard Tack - when the starboard side of the boat is windward.

Tacking - turning the bow of the boat through the eye of the wind.

Trim - to pull in... as in trim a sheet (line).

True Wind - the wind speed and direction as seen by a stationary observer.

Under trim - a condition where the sail is trimmed too loosely for the wind direction. The sail will luff if under-trimmed more than a slight amount.

Underway - when the boat is neither at anchor, made fast or aground.

Weather Helm - the tendency of a sailboat to head into the wind if the helm is released (letting go of the tiller).

Windward - the direction from which the wind is coming.