Windward, the direction from which the wind is blowing. The windward boat gets the wind before its opponent does and is in a generally favorable position.
Leeward, the direction the wind is blowing. Thus the leeward boat is downwind of its opponent.
Jib, a triangular foresail used when sailing into or across the wind.
Spinnaker, a huge, billowing foresail used for sailing downwind.
Sheet, a line used to tighten or slacken the sails.
Halyard, a line used to raise sails.
Stays, wires supporting the mast.
Spreaders, horizontal struts that force the stays out from the mast, thus providing greater support.
Luff, the forward edge of the sail.
To luff is...