The Collaborative International Dictionary of English v.0.48:
Cuirassier \Cui`ras*sier"\ (kw?`r?s-s?r"), n. [F. cuirassier. See Curass.] (Mil.) A soldier armed with a cuirass; especially, a soldier of the heaviest cavalry, wearing a cuirass only when in full dress. --Milton. [1913 Webster Webster 1913 Suppl.]WordNet (r) 3.0 (2006):
cuirassier n 1: a cavalryman equipped with a cuirass