The Collaborative International Dictionary of English v.0.48:
Milliard \Mil`liard"\ (F. m[-e]l`y[.a]r"; E. m[i^]l"l[i^]*[aum]rd), n. [F., from mille, mil, thousand, L. mille.] A thousand millions; -- usually called billion in the United States. See Billion. [1913 Webster]WordNet (r) 3.0 (2006):
milliard n 1: a billion; "in England they call one thousand million a milliard"