In its sense meaning "foolishly impractical especially in the pursuit of ideals" or "marked by rash lofty romantic ideas or extravagantly chivalrous action," quixotic honors Don Quixote de la Mancha, the chivalrous and eponymous hero of Miguel de Cervantes' 17th century satire, whose full title is Don Quixote de la Mancha, El ingeniosa hidalgo.

Don Quixote satirized the popular romances of the day. The title hero was born Alonso Quijano, and countless chivalric tales filled his head. The mock-knight set off for his own adventures and (not incidentally) to save the world, but returns to La Mancha a tired and disillusioned old man. The novel was widely translated, and within a few decades after the first English translations (1612 and 1620), the word Quixote had become a synonym for visionary or impractical idealist.

Added complexity comes from the fact that quixotic is usually pronounced \kwik-sä-tik\ even though the American pronunciation of Don Quixote is usually \dän-k-(h)-t\ . But note that the British avoid this discrepancy by pronouncing Don Quixote as \dän-kwik-st\ . One could try to straighten out these inconsistencies, but it would be like tilting at windmills.