quixotic

a. 1. Like Don Quixote; romantic to extravagance; prone to pursue unrealizable goals; absurdly chivalric; apt to be deluded. See also quixotism. “Feats of quixotic gallantry.” Prescott. [ 1913 Webster ]

2. Like the deeds of Don Quixote; ridiculously impractical; unachievable; extravagantly romantic; doomed to failure; as, a quixotic quest. [ PJC ]

The word “quixotic” . . . has entered the common language, with the meaning “hopelessly naive and idealistic, ” “ridiculously impractical, ” “doomed to fail.” That this epithet can be used now in an exclusively pejorative sense not only shows that we have ceased to read Cervantes and to understand his character, but more fundamentally it reveals that our culture has drifted away from its spiritual roots. Simon Leys (N. Y. Review of Books, June 11, 1998, p. 35) [ PJC ]