@ehBeth,
The die is cast is a famous quotation of Iulius Caesar. He is said to have told his troops as they crossed the Rubicon River in northern Italy in defiance of the Senate,
iacta alea est, "the die is cast." That is from Suetonius' historical biography
The Lives of the Twelve Caesars. Modern Latin mavens will tell you that it ought to be
alea iacta est; as Suetonius was born in Rome and was a native speaker of Latin, i'll take his word over that of contemporary Latin scholars.
Not only is die commonly used in the modern American language, but in gaming, as in board games and video games based on board games, die is even used in plural contexts. So, for example, in
Dungeon's and Dragons, by Wizards of the Coast, if the probability of an event is X out of ten, it will read "one die ten." But it goes on from there--if one casts the spell fireball, the damage is described as 6 die 6, meaning that six six-sided dice are thrown, ant the amount of damage--6 to 36 points--is determined by totaling the pips on top of the six dice. But it is expressed, invariably, as 6 die 6.
Until today, i had never in my life heard of anyone referring to a single die as "dice." I think i will compose an angry letter to
The Times.