Aplomb

aplomb \uh-PLOM\, noun:
Assurance of manner or of action; self-possession; confidence; coolness.

"Despite the tense atmosphere in the courtroom, the witness gave her statement with calmness and aplomb."

Aplomb is also a ballet term.

Opposite of doubt, insecurity, mistrust, uncertainty, anxiety, and peturbity.

Aplomb pudding is very nice at Christmastime.