Mickey Bayard has questions about the words die and dice.
A friend and I are in dispute over the expression, “The di (die , dye) is cast, we have crossed the Rubicon “. …our conflict is over the use of “di”. I feel it is the singular of Dice , and therefore means the casting of a single dice or di. My friend argues that it is related to a Die cast i.e. A Sword cast in metal from a die. Both seem plausible and the spelling should help , but I have seen it both ways ….So many people must be confused as well.
First, Caesar’s frequently quoted statement is usually rendered as The die is cast.
Alea iacta est (also alea jacta est, Latin: “The die has been cast”) is a Latin phrase attributed by Suetonius (as iacta alea est [ˈjakta ˈaːlea est]) to Julius Caesar on January 10, 49 BC as he led his army across the River Rubicon in northern Italy. –Wikipedia
Gambling was a favorite Roman pastime so Caesar’s metaphor was easily understood. Fate controlled the roll of the dice. By crossing the Rubicon, Caesar initiated the events that would play out in the civil war to follow.
The plural of this kind of die is dice.
I don’t know about swords, but coins and other objects are cast from a die:
An engraved stamp used for impressing a design or figure upon some softer material, as in coining money, striking a medal, embossing paper, etc.
The plural of this kind of die is dies.
The word die may come from Latin datum in the sense of “that which is given or decreed [as by lot or fortune].
The dots on dice are indented. The sense of “stamping block or tool” for die was first recorded in the 1690s.
There is historical precedent for using the plural “dice” as a singular, as in this example from the OED:
1751 MRS. E. HEYWOOD Hist. Betsy Thoughtless IV. 202 Protesting never to touch a card or throw a dice again.
Contemporary gamers frequently use “dice” as a singular:
The probability of one dice being a particular number is 1/6.
The player may use either ONE DICE or THE OTHER, instead of adding both Dice together, to increase their count.
Each player keeps one dice.
This use of “dice” to refer to one of the dotted cubes has recently crept into directions for games intended for general audiences.
The use of “dice” as a singular noun strikes my ear as incorrect, but I suspect that it will eventually become the norm.