Slot Machine
A narrow, elongated depression, groove, notch, slit, or aperture, especially one for receiving or admitting something, as a coin or a letter. Also: A position or assignment, as in a sequence or series: The program received a new time slot on the broadcasting schedule. A narrow opening, as in a typewriter: He slotted the letter into its proper place.
An elongated depression in the surface of a machine or device, into which coins or tokens can be dropped to activate one or more reels marked with varying symbols; a gambling machine. In the first ones, inserted coins fell onto an internal balance scale to tip it or spill other coins out; later devices had a circular display and a spinning indicator that came to rest on or pointed to a number, a colour, or a picture. Also called one-armed bandit, harpooned, and saloon machine. See also slot machine (def. 1).
The probability that a given symbol will appear on a particular reel depends on its weighting relative to the other symbols on that reel and the overall odds of winning. For example, the weighting of a JACKPOT symbol is lower than that of an orange. In addition, a given machine might have different payouts for different symbols. These issues are usually handled by a computer, which selects the stops for the reels without the visible symbols and explains them to the player with a display of what has been selected.