Sprezzatura

Sprezzatura (Italian) is a noun that means doing something effortlessly, with spontaneity and a certain nonchalance.  It has also been described as a way to disguise what one really desires, thinks or feels as a form of defense.  A performance that appears to be without effort. 

The word was coined in 1528 by Baldassare Castiglione, the author of  “The Book of Courtier”, a book about Renaissance court life. 

"Practise in everything a certain nonchalance that shall conceal design and show that what is done and said is done without effort and almost without thought.”   Baldassare Castiglione, The Book of the Courtier
  
"Norris is a man always in equipoise, a living illustration of the art of sprezzatura. No one has ever seen him ruffled.”    Hilary Mantel; Bring Up the Bodies; Henry Holt; 2012.