For historical context, here are the entries for quixotic that appear in Merriam-Webster's Collegiate Dictionary series, from the first edition (1898) through the eleventh (2003).
Webster's Collegiate Dictionary, first edition (1898):
Quixotic, a. Like Don Quixote; romantic to extravagance; absurdly chivalric; apt to be deluded. — Quixotically, adv.
Webster's Collegiate Dictionary, second edition (1910):
Webster's Collegiate Dictionary, third edition (1916):
quixotic, a. Like Don Quixote; romantic to extravagance; absurdly chivalric. — Syn. See VISIONARY. [The comment on quixotic under the entry for visionary is "quixotic implies extravagantly chivalrous devotion to visionary ideals; as, ... quixotic enthusiasm."] — -ically, adv. — quixotism, n.
Webster's Collegiate Dictionary, fourth edition (1931):
Webster's Collegiate Dictionary, fifth edition (1936):
quixotic, -otical, adj. [See DON QUIXOTE.] Like, or characteristic of, Don Quixote; idealistic but unpractical. — Syn. See VISIONARY. [The comment on quixotic under the entry for visionary is "quixotic implies extravagantly chivalrous devotion to visionary ideals."] — -otically, adv. — quixotism, n.
Webster's Collegiate Dictionary, sixth edition (1949):
quixotic, -otical, adj. [See DON QUIXOTE.] Like, or characteristic of, Don Quixote; idealistic but unpractical. — Syn. See IMAGINARY. [The comment on quixotic under the entry for imaginary is "quixotic implies an extravagantly chivalrous devotion to visionary ideals."] — quixotically, adv. — quixotism, n.
Webster's Collegiate Dictionary, seventh edition (1963):
quixotic adj {Don Quixote, hero of the novel Don Quixote de la Mancha (1605, 1615) by Cervantes} : idealistic to an impractical degree; esp : marked by rash lofty romantic ideas or extravagantly chivalrous action syn see IMAGINARY [The comment on quixotic under the entry for imaginary is "QUIXOTIC implies a devotion to romantic or chivalrous ideals unrestrained by ordinary prudence and common sense"] — quixotical adj — quixotically adv
Webster's Collegiate Dictionary, eighth edition (1973):
quixotic adj {Don Quixote, hero of the novel Don Quixote de la Mancha (1605, 1615) by Cervantes} : idealistic to an impractical degree; esp : marked by rash lofty romantic ideas or extravagantly chivalrous action — quixotical [This edition of the dictionary does not list quixotic as a synonym of imaginary or visionary] adj — quixotically adv
Merriam-Webster's Collegiate Dictionary, ninth edition (1983):
quixotic adj {Don Quixote} (1815) 1 : foolishly impractical esp. in pursuit of ideals; esp : marked by rash lofty romantic ideas or extravagantly chivalrous action 2 : CAPRICIOUS, UNPREDICTABLE syn see IMAGINARY [The comment on quixotic under the entry for imaginary is identical to the one that appeared in the seventh edition] — quixotical adj — quixotically adv
Merriam-Webster's Collegiate Dictionary, tenth edition (1993):
- [no change, except for the addition of an example—"a quixotic crusade"—to the note about quixotic as a synonym for imaginary in the entry for the latter word]
Merriam-Webster's Collegiate Dictionary, eleventh edition (2003):
Over the years, various minor changes in the Collegiates' handling of quixotic are evident. For example, in 1916, the dictionary dropped the wording "apt to be deluded" from the earlier definition; and in 1931, the dictionary replaced the disapproving language about extravagance and absurdly chivalric behavior in the entry for quixotic with the simpler and more neutral wording "idealistic but unpractical."
But bigger changes occurred in 1963, when, for the first time, the dictionary dropped the explicit association of the word quixotic with the character and behavior of the fictional character Don Quixote; and in 1983, when, out of nowhere, the dictionary introduced "capricious and unpredictable" as a second definition of the word.
I don't know what prompted the lexicographers at Merriam-Webster to introduce this second definition, but presumably they were persuaded that usage of the word in that sense was so widespread and firmly established to they could not in good descriptivist conscience ignore it.
When I read or hear someone using the word quixotic, my immediate reaction is to apply the characteristics of Don Quixote to the relevant context Those characteristics include chivalrousness, honor, impracticality, delusion, and steadfast devotion to a cause or quest.
This last characteristic is rather severely at odds with the attributes of capriciousness and unpredictability suggested by the new, second definition in the Ninth Collegiate; and I have to think that that conflicting meaning arose because people who had never read the book imagined that seeing windmills as giants (for example)—or believing a not very virtuous barmaid to be an almost saintly embodiment of feminine virtue—was an instance of capriciousness and unpredictability. In fact, as presented within the novel, they are signs of delusional thinking that is anything but inconsistent or capricious; perhaps the main poignancy of the novel lies in Don Quixote's virtuous fidelity to his duty, as he understands it, given his delusions.
But in the real world, people are not required to read (much less appreciate) Don Quixote before using the word quixotic. And it is hardly surprising that—in a society whose members are less and less familiar with literary classics from the ancient days before there was an Internet—words that originated as allusions to specific books and even to specific characters lose their mooring in popular culture and begin to be used in ways that are not at all true to their source.
