Your most impractical, head-in-the-clouds friend may be a Quixote. The noun is usually capitalized because it comes from the 17th-century novel “Don Quixote de la Mancha” by Miguel de Cervantes Saavedra. Originally written in Spanish, this novel is cited as one of the first modern novels, and it was so popular upon release that the words “quixotic” and “Quixote” were in use by the 1640s. The adjective “quixotic” isn’t usually capitalized because it’s been assimilated more into the common lexicon. The name Quixote, as from the book, is pronounced “kee-ho-tay,” but the noun Quixote has been adopted into English pronounced “kwik-suht.”