: idealistic and utterly impractical; especially : marked by rash lofty romantic ideas or chivalrous action doomed to fail
About the Word:
The novel Don Quixote de la Mancha by Miguel de Cervantes (published in 1605 and 1615), is widely regarded as one of the greatest works of literature ever. It also has given us a small, but useful, batch of words and phrases for describing that special kind of person who is unencumbered by common sense and the notion that grand gestures are often impractical.
The name of the hero of this work, Don Quixote, is used as a term for an impractical idealist. Used without the honorific Don, quixote by itself also refers to a quixotic person. And most common of all is that adjective, quixotic, used to refer to a person who is always "tilting at windmills" (a phrase denoting fighting imagined or illusory foes, taken from a scene in the book where Quixote attacks a windmill, thinking it a giant).
"Now, the wretched 'guardian' is himself deeply in love with the willful Margaret, and his Quixotic attempts to hasten her union with another man are mainly prompted by the feeling that it would be dishonourable for him to seek the hand of the wealthiest woman in England when he himself owes all he possesses to the generosity of her father." — The Speaker, 22 July 1899
— Ammon Shea
(Source: Merriam-Webster's Top 10 List: "Words that come from characters in books")