A narrow notch, groove, or opening, such as a keyway in machinery or the slit for coins in a vending machine. To move something into a slot: The car seat belt slotted easily into place.

In a game of chance, a position in the playing area where a player has a better opportunity to score, especially as a member of an attacking team in hockey. A winger or centre playing in the slot has a straight-on view of the net, which makes it difficult for a defender to deflect the puck.

The slots of a slot machine are arranged so that each reel has equal numbers of stops and a winning combination is more likely to occur when the symbols appear on earlier reels than in later ones. As a result, the odds of losing are often disproportionate to the frequency of winning symbols appearing on the physical reels.

The number of possible combinations is limited by the fact that only 22 symbols can fit into each slot, so a single symbol may not appear on multiple reels in a row. However, the manufacturers of modern electronic slot machines compensate for this by weighting the probability of each symbol appearing on a particular reel compared with its frequency on a different one. This enables the manufacturer to control the frequency with which each of the symbols appears on the payline. Slots are normal member functions, and their use enables signals to be connected to any number of other classes, regardless of whether those classes have public or private access. Together, signals and slots form a powerful component programming mechanism.