The story
Baldassare Castiglione coined it in The Book of the Courtier, 1528: a courtier should hide all his art and seem to act without effort. Menswear writers revived it for the loose tie and the unbuttoned cuff. English has nonchalance.
spret-sah-TOO-rah[sprettsaˈtuːra]
studied carelessness that hides the effort — nonchalance
Closest in English: nonchalance, effortlessness, insouciance. None of them covers it.
Baldassare Castiglione coined it in The Book of the Courtier, 1528: a courtier should hide all his art and seem to act without effort. Menswear writers revived it for the loose tie and the unbuttoned cuff. English has nonchalance.
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Harder than most words so far.