Sometimes, you see a word and think you can guess its meaning based on similar looking or sounding others. Aleatory was one of those for me. Perhaps it says more about my lifestyle than my etymological skills that I thought it was something to do with drinking beer. And who wouldn’t? Why, it starts with ale, and that’s as good a way to start a word as any other. The suffix, –atory, is an adjective-forming element that often means “relating to or characterized by.” Thus, aleatory means “related to the drinking of ale, or beer.”
But it doesn’t. It’s a classic lesson of how you can create a wonderful and verisimilous etymology, which still turns out to be wrong. Pseudoetymologies (sometimes called “folk etymologies” ) can sound very convincing, erroneous as they may ultimately turn out to be. For example, the word isle sounds as if it is simply a shortened form of the word island. However, it actually comes from the Latin word insula, meaning “island,” whereas island comes from the Old English iegland, which also means “island.” So similar as they may seem, they have different roots. 
So what of aleatory? If it has nothing to do with ale, what does it mean? According to the OED, it’s an adjective used to refer to things that are;
Dependent on uncertain events or occurrences; haphazard, random.
It’s to do with chance and comes from the Latin word aleatorius, which means “connected to gamblers or games of chance. An aleator is a dice player or gambler in general, and the word alea means “dice.” The suffix is the same as my false definition and so the word is “pertaining to the use of dice” i.e. gambling and betting.
It first turns up in 1693 in The third book of the works of Mr. Francis Rabelais, translated by Thomas Urquhart and Peter Anthony Motteux, in the sentence, “So continually fortunate in that Aleatory way of deciding Law Debates.” This referred to the way the judge being written about would determine the outcome of cases – by throwing a die.
In the 1960’s, it became more specifically used to refer to works of art or music that were “created, composed, or performed according to chance. In modern times, the composer John Cage (1912-1992) wrote and performed “Music of Changes” in 1951, which used the I Ching to determine elements of the composition. Such aleatory music was taken up by other musicians such as Pierre Boulez (born 1925) and Karlheinz Stockhausen (1928-2007).
The word is more likely to occur in the legal profession when used to refer to an aleatory contract. This is defined as;
A mutual agreement between two parties in which the performance of the contractual obligations of one or both parties depends upon a fortuitous event.
The most common example is probably an insurance contract. Here, you insure yourself or your property against damage due to a rare or unlikely event – such as a a meteorite hitting your car. An “Act of God” is an aleatory phenomenon. The insurance company doesn’t have to do anything unless the chance event takes place.
And if you’re feeling in the mood for reading an aleatory novel, get hold of The Dice Man by Luke Rhinehart. Published in 1971, it’s the story of how a jaded psychiatrist takes to determining his life by throwing dice. Kindle readers will have to track down the actual physical book as it’s not available in that format but Nook owners can get it right now.
 In linguistics, the phrase folk etymology has a very specific meaning that differs from the popular usage. It is used to describe how a word changes over time due to the influence of more familiar words or phrases. The word crayfish originally came from the French crevis, but the latter part sounded so much like “fish” that it became “crayfish.”
 A folk etymology can ruin a political career. On January 15th, 1999, David Howerd, an aide to the then Mayor of Washington, Anthony Williams, made a reference to the budget as being “niggardly,” which means “mean” or “stingy.” However, a less etymologically orientated staffer (identified as one Marshall Brown) complained that he was offended by what he took as a “racial slur.” Howerd tendered his resignation a week later. The assumption was that niggardly and nigger were related i.e. the same root, which is, in fact, totally wrong. Niggardly has its roots in Old Icelandic hnøggr whereas nigger can be traced back to Latin niger meaning “black.” Just because words sound the same doesn’t mean they mean the same or come from the same root.