From Miguel de Cervantes' Don Quixote (pronounced 'don kee-ho-tee'). Don Quixote was a crazy old man who thought he was a knight. He went about trying to do noble deeds, but was in fact only managed to make a fool of himself. Quixotic is pronounced 'kwik-sad-ik', or 'kwik-sot-ik'.
It means:
1. Foolish, impractical, wild-eyed; idealistic without regard to practicality.
2. Capricious, unpredictable, or impulsive.
3. Romantic to extravagance; absurdly chivalric.
4. Not worried about practical matters; unrealistic.
Other forms of this most excellent word include: quixotical, quixotically, quixotism, quixotry, quixotize.