Definition: something (such as a business venture) that has an unpredictable outcome
Crapshoot is typically encountered today written as a closed compound (single word), but when it first entered the language in the late 19th century it was generally an open compound (“crap shoot”). And no, the crap portion of this word was not a judgmental adjective — it was referring to the game of craps, a gambling game in which a pair of dice are thrown (or shot).
By the middle of the 20th century the shooting of craps was being used, in one way or another, to indicate unpredictability in some venture: an article on boiler rooms in the Chicago Daily Tribune in 1956 says “The aim has been to distinguish between sound investment objectives and income and ‘the old crap shooting game of speculation.’”
The bill states: Complainant would respectfully show to the court that the defendants, as partners or otherwise, are now and have been for the past three months or more engaged in running a gambling house, or, to use the parlance of defendant, a “crap shoot” … that in said house they operate and run a gambling game or game of chance known as “craps,” which is played in the following manner….
—The Tennessean (Nashville, TN), 12 Jan. 1890