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A position in a schedule, plan, or sequence: I could slot you in at 2 p.m.
A space for a reel or other part: There are several slots in the wing of this airplane.

An allocation of a time and place for an aircraft to take off or land, as authorized by an airport or air-traffic authority: We have 40 more slots for the new airline at U.S. airports.

In gambling, a slot is the space on a slot machine where symbols appear; a particular combination of symbols on a specific reel causes the player to win money. The probability of each possible symbol appearing in a slot is determined by the microprocessors in modern slots, and varies by game. Each slot has a different pay table and its own set of unique features.

Slots also include rows, which run across the reels from left to right. Rows can include anywhere from one to 50 symbols, and the number of symbols that appear in each slot varies by game. Whether a slot is mechanical, like the physical machines you’ll find in casinos, or software-driven, as in online slots, each possible combination of symbols is assigned a random number by the slot machine’s microprocessor. This random-number generator then sets a combination of numbers to spin into the slot’s reels.

Some people believe that a slot that hasn’t paid off for a long time is “due to hit.” This belief is flawed, however, because each spin of the slot machine has the same odds of hitting a winning combination.