The Collaborative International Dictionary of English v.0.48:

Sang-froid \Sang`-froid"\, n. [F., cold blood.]
   Freedom from agitation or excitement of mind; coolness in
   trying circumstances; indifference; calmness. --Burke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sang-froid
    n 1: great coolness and composure under strain; "keep your cool"
         [syn: aplomb, assuredness, cool, poise, sang-
         froid]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "sang-froid":
   Buddha-like composure, Oriental calm, aloofness, aplomb, ataraxy,
   balance, balanced personality, calm disposition, calm of mind,
   calmness, composure, constancy, cool, coolheadedness, coolness,
   coolth, countenance, courage, easy mind, equanimity, equilibrium,
   fastness, firmness, homeostasis, icy calm, imperturbability,
   imperturbation, indifference, indisturbance, invariability,
   mental composure, nerve, peace of mind, peacefulness,
   philosophic composure, philosophicalness, philosophy, phlegm,
   placidity, poise, quiet, quiet mind, quietude, reliability,
   rootedness, sang-froid, secureness, security, self-containment,
   self-control, self-possession, serenity, solidity, soothingness,
   soundness, stability, stable equilibrium, stable state,
   steadfastness, steadiness, steady nerves, steady state,
   substantiality, tranquillity, unconcern, undeflectability,
   uniformity, unruffledness, unshakable nerves, unshakableness