Lee is the side of something that's sheltered from the wind. If you're standing behind a building on a windy day and suddenly the air feels calm, you're in the lee of that building. The wind hits one side while the other side stays protected and peaceful.

Sailors use this word constantly because it matters which side of their boat faces the wind. The lee side (or leeward side) is the sheltered side, away from where the wind is blowing from. The opposite is the windward side, which takes the full force of the wind. When a ship drops anchor in the lee of an island, it's using the island as a giant windbreak, finding calmer water on the protected side.

You might read about soldiers taking cover in the lee of a hill during a battle, or hikers camping in the lee of a rock formation to escape a mountain wind. The concept is always the same: finding the calm spot behind something solid when the wind is blowing hard.