A narrow notch or opening, as in a door or window; also: a position in a line or sequence; a vacancy; a niche. (OED)
A slit or opening into which something may be fitted, as in a slot machine or a magazine. A narrow notch or groove, as in a keyway on an electromechanical slot machine, or the hole for a coin in a vending machine.
An area of an airplane or other vehicle in which passengers are seated. Often, a single plane or train can only fit a certain number of people in its cabins and on its tracks. Consequently, airlines and train companies must allocate slots for their customers in order to avoid overcrowding. This is called flow management.
In a computer program, a slot is a dynamic placeholder that either waits for content (a passive slot) or calls out to a renderer to fill it in. The contents of a slot are dictated by the scenario that the slot is placed in (Add Items to Slot) or by a targeter that the slot is filled with (Add Target to Slot).
A game machine where players insert cash or, in “ticket-in, ticket-out” machines, paper tickets with barcodes, and activate reels to arrange symbols into combinations that win credits according to the machine’s pay table. Symbols vary with each machine, but classic symbols include fruits, bells and stylized lucky sevens. Many slot games have a theme and bonus features aligned with it.
Progressive jackpot slots are popular, particularly in casinos where the machines in a room or across a city are linked to grow the same jackpot. Those jackpots are usually displayed on the machines and are updated minute by minute. In addition to the traditional casino setting, progressive jackpot slots are available online, with casino sites linking their desktop and mobile games to a common system.
Statistically speaking, a slot is just as likely to pay out soon after resetting as it is after months of not paying out. However, most players choose to play a different machine once a particular one has proven that it is not a good bet.
One way to judge whether a machine is worth playing is to note its jackpot size on every visit. When the jackpot decreases, compare it to your last noted jackpot size and make a decision. You can do this as many times as you like, but it will probably take at least half a dozen visits. If you are patient, your research will pay off. Good luck!