Quixotism (// or //; adj. quixotic) is impracticality in pursuit of ideals, especially those ideals manifested by rash, lofty and romantic ideas or extravagantly chivalrous action. It also serves to describe an idealism without regard to practicality. An impulsive person or act might be regarded as quixotic.
Quixotism as a term or a quality appeared after the publication of Don Quixote in 1605. Don Quixote, the hero of this novel, written by Spanish author Miguel de Cervantes Saavedra, dreams up a romantic ideal world which he believes to be real, and acts on this idealism, which most famously leads him into imaginary fights with windmills that he regards as giants, leading to the related metaphor of "tilting at windmills".
Already in the 17th century the term quixote was used to describe a person who does not distinguish between reality and imagination. The poet John Cleveland wrote in 1644, in his book The character of a London diurnall:
The Quixotes of this Age fight with the Wind-mills of their owne Heads.
The word quixotism is mentioned, for the first time, in Pulpit Popery, True Popery (1688):
...all the Heroical Fictions of Ecclesiastical Quixotism...