Leeward is the side of a boat away from the direction where the wind is coming (i.e., the side towards which the wind is moving). Also known as the "low side". The opposite of leeward is windward.
The terms "leeward" and "windward" are also used in reference to islands in an archipelago and to the different sides of a single island. In the latter case, the windward side is that side of an island subject to the prevailing wind, and is thus the wetter side (see orographic precipitation). The leeward side is the side protected by the elevation of the island from the prevailing wind, and is typically the drier side of an island. Thus, leeward and windward are important weather and climate factors on oceanic islands.
In the case of an archipelago, "leeward islands" are the islands downwind.
The leeward side is the side protected by the elevation of the island from the prevailing wind, and is typically the drier side of an island.
In the case of an archipelago, "windward islands" are upwind and "leeward islands" are the downwind ones.
Windward and leeward directions are important factors to consider when sailing a sailing ship, though the terms have largely fallen out of use in favour of "head-to-wind" and "downwind", see points of sail.