To disorient is to confuse or cause to lose all sense of direction. Stepping off an airplane halfway around the world in the middle of the night will disorient even the most experienced traveler.
Disorient comes from the French désorienter, which means "to lose one's bearings" but literally translates to "to turn from the east." The Latin root is orientem, "the part of the sky where the sun rises." When we orient ourselves, we get our bearings, figuring out which direction we're facing. It disorients you to lose track of where you are, or to feel befuddled or confused: "That medicine always disorients my cat, making him stumble around bumping into things"