Wind-related terminology:

Downwind - The direction the wind is blowing towards, or to leeward. When an individual is facing downwind, the wind is at their back.

Power Zone - area within the wind window downwind of the pilot that generates greatest force; 

Sideshore - Winds blowing parallel to the shore. Usually the most desirable direction for kitesurfing.

Side onshore - Wind blowing between sideshore and at a 45 degree angle towards the shore, also quite desirable for kiteboarding.

Upwind - The direction from which the wind is blowing; windward; into the wind.

Wind window - The area in which a kite can fly in relation to the wind direction; If the rider somehow puts the kite out of the window , for example, by riding downwind very quickly and sending the kite directly overhead and behind , the kite will stall and frequently fall out of the sky.