From Baldassare Castiglione‘s Book of the Courtier.
Simply, sprezzaturra is the ability to appear to succeed without effort, to have “an easy facility in accomplishing difficult actions which hides the conscious effort that went into them” or to appear ‘artfully artless’.
It’s the art of appearing extremely capable, of hiding the effort behind one’s actions and achievements, and never letting on that you might be anything less than supremely confident. It’s something we all strive for in some domain, be it effortless creating culinary masterpieces, dancing a perfect tango, or walking a tightrope. I wouldn’t go so far as to say that it’s the main reason all of us spend effort learning skills, particularly ones that aren’t of practical use, but I do think it’s intrinsically human to get a certain thrill whenever you apply effort, succeed, and have someone say “Oh, you make it look so easy..”
via a TED talk by Virginia Postrel on glamour.