A slot is a narrow opening for receiving or admitting something, as a coin or a letter. In aviation, a slot is an authorization by an airport or air-traffic control to take off or land at a specific time during a specified period of time: Air traffic controllers allocate slots to planes according to their expected flight paths and the amount of traffic they expect to encounter at the airport.
In a slot machine, a win occurs when symbols align along pay lines on the reels. These lines can be horizontal, vertical, diagonal, zig-zag shaped, or even star shaped, and can have multiple payout values depending on the number of matching symbols and what type of bonus features the slot has. Some machines have more than one pay line per spin, and the number of tokens inserted determines how many paylines are active.
A slot may also refer to an allocated position or time: The job of chief copy editor was his slot at the Gazette. A slot can also be a grammatical feature: In tagmemics, a grammatical slot is an element of a construction into which a word can be fit.