Quixotic is a term derived from the unrealistically idealistic character of Don Quixote in Cervantes' 17th century novel Don Quixote de la Mancha. The term refers to a person whose ideals are huge but who lacks practical or reasonable understanding about why such ideals cannot be achieved.
Some definitions further add that a person who is quixotic is impulsive, capricious, or a dreamer of impossible dreams, as per the Man of La Mancha song. Further, this individual might have no regard for money, and might be an elaborate spender or eschew the riches of the world.
Additionally, a person who is chivalrous to the point of absurdity might be termed quixotic. For example, a man who knocks people out of the way to open a door for lady is absurdly chivalrous, and thus could be said to meet this definition.
Quixotic people are in some ways enviable, as they tend not to be weighed down by the oppression of reality. For example, one can look at the idealistic ambitions of children, which don’t necessarily reflect realism. The two-year-old who wants to grow up and become an astronaut may not understand why such a goal is extremely difficult, but that doesn't mean his or her dreams should be discouraged.
A young girl who wants to grow up and become a Catholic Priest is quixotic in a more true sense. Unless Rome changes its policy, the girl may dream about it as much as she likes but has no possibility of fulfilling her dream. When the girl insists she will grow up to marry a rock star — or even something more unrealistic, like a horse — she is waxing quixotic. It’s a romantic state of dreaminess that has nothing to do with reality. It’s often a deep reach into the longing of the ideal state, and the ideal world, where all things most desired surround a person.
Few still tilt at windmills when the hard realities of life descend on them. Yet many people still entertain hopes that a lottery ticket will make them millionaires or that suddenly the world will become peaceful. Indulging in the occasional idealistic dream is probably helpful since it gives people, if only momentarily, the things they prize most dearly. People who are unable to separate these dreams from reality, however, may need professional help.