Doozy

wiktionary

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Unknown. Perhaps from daisy (the flower) or the name of Italian actress Eleonora Duse. The automobile manufacturer Duesenberg is often erroneously cited as the etymology of doozy; while seemingly sensical, the original usage of the latter predates the former by more than a decade.

etymonline

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doozy

also doozie, 1903 (adj.) "excellent, splendid," 1916 (n.), "an excellent of splendid thing or person," perhaps an alteration of daisy, or from popular Italian actress Eleonora Duse (1859-1924). In either case, reinforced by Duesenberg, the expensive, classy make of automobile from the 1920s-30s.