sang-froid - sahn-FRAH - cold-blooded coolness
Example: "World nations are stumped by North Korea's sang-froid atomic testing."
As a starter: and as a former teacher in English, I hope to add to reader's vocabulary by presenting a word a day in simple terms that anyone can understand - from current use in publications, radio,TV, etc. Remember: use a new word three times in a day and it's yours forever!